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Letta

Letta (formerly MemGPT) is a stateful AI agents platform built around long-term memory, tool execution, and multi-agent coordination. The Letta REST API exposes 239 endpoints across 36 public resource categories — agents, memory blocks, archival memory, sources (RAG), custom tools (sandboxed/client-side/MCP), MCP servers, multi-agent groups, identities, runs, scheduled messages, and a streaming voice-mode endpoint. Open-source server (Apache-2.0, 22.9k+ stars) is available on GitHub; Letta Cloud is the managed offering; the Agent Development Environment (ADE) provides a web UI for inspecting context windows, memory blocks, and run history. Python and TypeScript SDKs ship alongside the REST API, and the open `.af` agent file format lets agents migrate between deployments.

agent ready

Real signal across most facets with visible, nameable gaps — the contract exists but is thin, or the portal is good while governance and commercial terms are absent.

Kin Score

API Evangelist profiles Letta the way a machine reads it — 443 machine-readable artifacts across 41 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.

Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Letta scores 58.8/100 (developing), with a separate agent-readiness read of 48/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.

Kin Score

This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 58.8/100 · developing
Contract Quality 18.8 / 25
Developer Ergonomics 4.3 / 20
Commercial Clarity 12.6 / 20
Operational Transparency 3.4 / 13
Governance 10.4 / 12
Discoverability 9.3 / 10
Agent readiness — 48/100 · agent ready
Machine-Readable Contract 18 / 18
Agentic Access Contract 15 / 15
MCP Server 0 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 7 / 7
Typed Event Surface 0 / 6
Agent Skills 0 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3

How we profile Letta

Each block below is one kind of artifact we hold for Letta. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.

APIs 41

Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.

Individual APIs this provider publishes, each with its own machine-readable definition.

Letta Code

Letta's memory-first coding agent — a CLI plus a desktop app (and an action for GitHub repos). "The memory-first coding agent that remembers and learns." Builds on the Letta Cod...

Letta Admin API

Administrative operations (org / billing / policy).

Letta Agents API

Create, list, modify, export, and delete stateful agents with memory and tools.

Letta Archives API

Manage archival memory archives and passages (RAG-style long-term store).

Letta Blocks API

Manage in-context memory blocks (core memory) shared across agents.

Letta Chat API

Chat operations.

Letta Client-Side Access Tokens API

Mint short-lived client-side access tokens for browser/mobile use.

Letta Conversations API

Conversational session threads anchored to an agent.

Letta Device Storage API

Per-device storage for the Letta Code SDK and ADE.

Letta Embeddings API

List configured embedding models.

Letta Environments API

Environment variables and configuration scoped to agents/tools.

Letta Feeds API

Subscribed feeds that drive agents.

Letta Folders API

Organize agents and resources into folders.

Letta Groups API

Coordinate multi-agent groups (supervisor/worker, round-robin, sleep-time).

Letta Health API

Service health/readiness endpoint.

Letta Identities API

Map external user identities to agents and memory contexts.

Letta Internal Agents API

Internal Agents operations.

Letta Internal Blocks API

Internal Blocks operations.

Letta Internal Runs API

Internal Runs operations.

Letta Internal Templates API

Internal Templates operations.

Letta Jobs API

Manage long-running background jobs (e.g., file ingestion).

Letta LLMs API

List available LLM models and configurations.

Letta MCP Servers API

Register external Model Context Protocol servers and expose their tools to agents.

Letta Memory Files API

Memory-mapped file resources attached to agents.

Letta Messages API

Send messages, list message history, search, and batch operations.

Letta Metadata API

Service/runtime metadata.

Letta Models API

List available chat and embedding models exposed by configured providers.

Letta Passages API

Individual archival memory passages (chunked context).

Letta Pipelines API

Composable agent pipelines.

Letta Projects API

Project-level scoping for agents and resources.

Letta Providers API

Configure LLM provider credentials (OpenAI, Anthropic, Azure, Ollama, etc.).

Letta Runs API

Inspect and manage agent runs (executions of an agent in response to a message).

Letta Sandboxes API

Manage code-execution sandboxes used by sandbox tools.

Letta Scheduled Messages API

Schedule one-time or recurring messages to drive agents over time.

Letta Sources API

Manage data sources (files, URLs) used to populate agent archival memory.

Letta Steps API

Per-step traces of an agent run.

Letta Tag API

Tag-based filtering metadata.

Letta Telemetry API

Run-step traces and observability data.

Letta Templates API

Reusable agent templates for instantiation.

Letta Tools API

Register and execute custom tools (sandboxed Python, client-side, MCP).

Letta Voice API

Voice (low-latency) chat completions endpoint for agents.

Scroll within the panel for all 41 ·

Open Collections 1

Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

Letta API

OPEN COLLECTION

Pricing Plans 1

Pricing is part of the interface. Machine-readable plans tell you what a tier costs and includes before you commit — one of the six things the Kin Score reads for commercial clarity.

Published pricing tiers and plan structures.

Letta Plans Pricing

3 plans

PLANS

Rate Limits 1

Rate limits are the difference between a demo that works and a production integration that doesn't fall over. Publishing them is an operational-transparency signal — and a hard requirement for any agent that plans its own throughput.

Documented rate limits and quota policies.

Letta Rate Limits

2 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals let a buyer model the financial operations of an API before it's live. We profile them for the same reason we profile pricing: the money is part of the contract.

Cost, billing, and metering signals for API financial operations.

Letta Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts give the data shared meaning across APIs. We profile them because semantics are what let a machine reconcile 'customer' here with 'customer' somewhere else.

JSON-LD contexts and semantic vocabularies used across these APIs.

Letta Context

35 classes · 34 properties

JSON-LD

Spectral Rules 1

Governance rulesets we run against this provider's specs — the automated checks behind parts of the score. Profiling them makes the quality bar explicit and re-runnable, not a matter of opinion.

Letta API Rules

6 rules · 5 warnings

SPECTRAL

JSON Schema 349

Standalone JSON Schema definitions describe the data models behind the API. We profile them so the shapes are validatable on their own — useful long after a single request is forgotten.

Standalone JSON Schema definitions for this provider's data models.

AgentState

45 properties

JSON SCHEMA

AgentEnvironmentVariable

10 properties

JSON SCHEMA

AgentFileAttachment

10 properties

JSON SCHEMA

AgentFileSchema

10 properties

JSON SCHEMA

AgentState

45 properties

JSON SCHEMA

AgentType

0 properties

JSON SCHEMA

Annotation

2 properties

JSON SCHEMA

AnnotationURLCitation

4 properties

JSON SCHEMA

AnthropicModelSettings

9 properties

JSON SCHEMA

AnthropicThinking

2 properties

JSON SCHEMA

ApprovalCreate

7 properties

JSON SCHEMA

ApprovalRequestMessage

12 properties

JSON SCHEMA

ApprovalResponseMessage

14 properties

JSON SCHEMA

ApprovalReturn

4 properties

JSON SCHEMA

ArchivalMemorySearchResponse

2 properties

JSON SCHEMA

ArchivalMemorySearchResult

4 properties

JSON SCHEMA

Archive

10 properties

JSON SCHEMA

ArchiveCreateRequest

4 properties

JSON SCHEMA

ArchiveUpdateRequest

2 properties

JSON SCHEMA

AssistantMessage

11 properties

JSON SCHEMA

AssistantMessageListResult

6 properties

JSON SCHEMA

Audio

1 properties

JSON SCHEMA

AuthRequest

1 properties

JSON SCHEMA

AuthResponse

2 properties

JSON SCHEMA

AzureModelSettings

5 properties

JSON SCHEMA

Base64Image

4 properties

JSON SCHEMA

BasetenModelSettings

4 properties

JSON SCHEMA

BaseToolRuleSchema

2 properties

JSON SCHEMA

BatchJob

18 properties

JSON SCHEMA

BedrockModelSettings

5 properties

JSON SCHEMA

BillingContext

3 properties

JSON SCHEMA

Block

19 properties

JSON SCHEMA

BlockResponse

19 properties

JSON SCHEMA

BlockSchema

17 properties

JSON SCHEMA

BlockUpdate

16 properties

JSON SCHEMA

Body_export_agent

2 properties

JSON SCHEMA

Body_import_agent

13 properties

JSON SCHEMA

Body_upload_file_to_folder

1 properties

JSON SCHEMA

Body_upload_file_to_source

1 properties

JSON SCHEMA

CancelAgentRunRequest

1 properties

JSON SCHEMA

ChatCompletion

8 properties

JSON SCHEMA

ChatCompletionAssistantMessageParam

7 properties

JSON SCHEMA

ChatCompletionAudio

4 properties

JSON SCHEMA

ChatCompletionContentPartImageParam

2 properties

JSON SCHEMA

ChatCompletionContentPartRefusalParam

2 properties

JSON SCHEMA

ChatCompletionContentPartTextParam

2 properties

JSON SCHEMA

ChatCompletionDeveloperMessageParam

3 properties

JSON SCHEMA

ChatCompletionFunctionMessageParam

3 properties

JSON SCHEMA

ChatCompletionMessage

7 properties

JSON SCHEMA

ChatCompletionMessageCustomToolCall

3 properties

JSON SCHEMA

ChatCompletionMessageFunctionToolCall

3 properties

JSON SCHEMA

ChatCompletionMessageFunctionToolCall

3 properties

JSON SCHEMA

ChatCompletionRequest

11 properties

JSON SCHEMA

ChatCompletionSystemMessageParam

3 properties

JSON SCHEMA

ChatCompletionToolMessageParam

3 properties

JSON SCHEMA

ChatCompletionUserMessageParam

3 properties

JSON SCHEMA

ChatGPTOAuthModelSettings

5 properties

JSON SCHEMA

ChatGPTOAuthReasoning

1 properties

JSON SCHEMA

ChildToolRule

5 properties

JSON SCHEMA

ChildToolRuleSchema

3 properties

JSON SCHEMA

Choice

4 properties

JSON SCHEMA

ClientSkillSchema

3 properties

JSON SCHEMA

ClientToolSchema

3 properties

JSON SCHEMA

CodeInput

2 properties

JSON SCHEMA

CompactionResponse

3 properties

JSON SCHEMA

CompactionSettings

7 properties

JSON SCHEMA

CompactionSettings

7 properties

JSON SCHEMA

CompactionStats

6 properties

JSON SCHEMA

ComparisonOperator

0 properties

JSON SCHEMA

CompletionTokensDetails

4 properties

JSON SCHEMA

CompletionUsage

5 properties

JSON SCHEMA

ConditionalToolRule

6 properties

JSON SCHEMA

ConditionalToolRuleSchema

5 properties

JSON SCHEMA

ContextWindowOverview

23 properties

JSON SCHEMA

ContinueToolRule

3 properties

JSON SCHEMA

Conversation

12 properties

JSON SCHEMA

ConversationMessageRequest

21 properties

JSON SCHEMA

CoreMemoryBlockSchema

9 properties

JSON SCHEMA

CreateAgentRequest

48 properties

JSON SCHEMA

CreateArchivalMemory

3 properties

JSON SCHEMA

CreateBatch

2 properties

JSON SCHEMA

CreateBlock

16 properties

JSON SCHEMA

CreateConversation

4 properties

JSON SCHEMA

CreateMCPServerRequest

2 properties

JSON SCHEMA

CreateSSEMCPServer

5 properties

JSON SCHEMA

CreateStdioMCPServer

4 properties

JSON SCHEMA

CreateStreamableHTTPMCPServer

5 properties

JSON SCHEMA

Custom

2 properties

JSON SCHEMA

Custom

2 properties

JSON SCHEMA

DeepseekModelSettings

5 properties

JSON SCHEMA

DeleteDeploymentResponse

4 properties

JSON SCHEMA

DeploymentEntity

6 properties

JSON SCHEMA

DuplicateFileHandling

0 properties

JSON SCHEMA

DynamicManager

4 properties

JSON SCHEMA

DynamicManagerSchema

4 properties

JSON SCHEMA

DynamicManagerUpdate

4 properties

JSON SCHEMA

E2BSandboxConfig

3 properties

JSON SCHEMA

EmbeddingConfig

10 properties

JSON SCHEMA

EmbeddingConfig

10 properties

JSON SCHEMA

EmbeddingModel

15 properties

JSON SCHEMA

EventMessage

12 properties

JSON SCHEMA

ExportAgentRequest

3 properties

JSON SCHEMA

FeedbackType

0 properties

JSON SCHEMA

File

2 properties

JSON SCHEMA

FileAgentSchema

10 properties

JSON SCHEMA

FileBlock

23 properties

JSON SCHEMA

FileFile

3 properties

JSON SCHEMA

FileMetadata

16 properties

JSON SCHEMA

FileProcessingStatus

0 properties

JSON SCHEMA

FileSchema

14 properties

JSON SCHEMA

FileStats

3 properties

JSON SCHEMA

Folder

10 properties

JSON SCHEMA

Function

2 properties

JSON SCHEMA

FunctionCall

2 properties

JSON SCHEMA

FunctionCall

2 properties

JSON SCHEMA

FunctionDefinition

4 properties

JSON SCHEMA

FunctionTool

2 properties

JSON SCHEMA

GeminiThinkingConfig

2 properties

JSON SCHEMA

GenerateRequest

4 properties

JSON SCHEMA

GenerateResponse

3 properties

JSON SCHEMA

GenerateToolInput

5 properties

JSON SCHEMA

GenerateToolOutput

3 properties

JSON SCHEMA

GoogleAIModelSettings

6 properties

JSON SCHEMA

GoogleVertexModelSettings

6 properties

JSON SCHEMA

GroqModelSettings

5 properties

JSON SCHEMA

Group

18 properties

JSON SCHEMA

GroupCreate

6 properties

JSON SCHEMA

GroupSchema

7 properties

JSON SCHEMA

GroupUpdate

5 properties

JSON SCHEMA

Health

2 properties

JSON SCHEMA

HiddenReasoningMessage

12 properties

JSON SCHEMA

HTTPValidationError

1 properties

JSON SCHEMA

Identity

8 properties

JSON SCHEMA

IdentityCreate

7 properties

JSON SCHEMA

IdentityProperty

3 properties

JSON SCHEMA

IdentityPropertyType

0 properties

JSON SCHEMA

IdentityType

0 properties

JSON SCHEMA

IdentityUpdate

6 properties

JSON SCHEMA

IdentityUpsert

7 properties

JSON SCHEMA

ImageContent

2 properties

JSON SCHEMA

ImageURL

2 properties

JSON SCHEMA

ImportedAgentsResponse

1 properties

JSON SCHEMA

InitToolRule

4 properties

JSON SCHEMA

InputAudio

2 properties

JSON SCHEMA

InternalTemplateAgentCreate

50 properties

JSON SCHEMA

InternalTemplateBlockCreate

16 properties

JSON SCHEMA

InternalTemplateGroupCreate

9 properties

JSON SCHEMA

Job

18 properties

JSON SCHEMA

JobStatus

0 properties

JSON SCHEMA

JobType

0 properties

JSON SCHEMA

JsonObjectResponseFormat

1 properties

JSON SCHEMA

JsonSchemaResponseFormat

2 properties

JSON SCHEMA

AgentSchema

53 properties

JSON SCHEMA

MessageSchema

19 properties

JSON SCHEMA

ToolSchema

18 properties

JSON SCHEMA

ToolReturn

6 properties

JSON SCHEMA

ToolExecuteRequest

1 properties

JSON SCHEMA

UpdateSSEMCPServer

5 properties

JSON SCHEMA

UpdateStdioMCPServer

4 properties

JSON SCHEMA

UpdateStreamableHTTPMCPServer

5 properties

JSON SCHEMA

UpdateSSEMCPServer

4 properties

JSON SCHEMA

UpdateStdioMCPServer

2 properties

JSON SCHEMA

UpdateStreamableHTTPMCPServer

5 properties

JSON SCHEMA

ToolReturn

5 properties

JSON SCHEMA

ToolReturn

5 properties

JSON SCHEMA

ChatCompletionTokenLogprob

4 properties

JSON SCHEMA

ChoiceLogprobs

2 properties

JSON SCHEMA

TopLogprob

3 properties

JSON SCHEMA

AgentSchema

19 properties

JSON SCHEMA

MessageSchema

10 properties

JSON SCHEMA

ToolSchema

12 properties

JSON SCHEMA

CompactionRequest

1 properties

JSON SCHEMA

CompactionRequest

2 properties

JSON SCHEMA

ToolExecuteRequest

1 properties

JSON SCHEMA

LettaAssistantMessageContentUnion

0 properties

JSON SCHEMA

LettaAsyncRequest

17 properties

JSON SCHEMA

LettaBatchMessages

1 properties

JSON SCHEMA

LettaBatchRequest

17 properties

JSON SCHEMA

LettaErrorMessage

6 properties

JSON SCHEMA

LettaImage

5 properties

JSON SCHEMA

LettaMessageContentUnion

0 properties

JSON SCHEMA

LettaMessageUnion

0 properties

JSON SCHEMA

LettaPing

10 properties

JSON SCHEMA

LettaRequest

16 properties

JSON SCHEMA

LettaRequestConfig

4 properties

JSON SCHEMA

LettaResponse

5 properties

JSON SCHEMA

LettaStopReason

2 properties

JSON SCHEMA

LettaStreamingRequest

20 properties

JSON SCHEMA

LettaStreamingResponse

0 properties

JSON SCHEMA

LettaToolReturnContentUnion

0 properties

JSON SCHEMA

LettaUsageStatistics

10 properties

JSON SCHEMA

LettaUserMessageContentUnion

0 properties

JSON SCHEMA

ListDeploymentEntitiesResponse

4 properties

JSON SCHEMA

LLMConfig

27 properties

JSON SCHEMA

LLMConfig

27 properties

JSON SCHEMA

LocalSandboxConfig

4 properties

JSON SCHEMA

ManagerType

0 properties

JSON SCHEMA

MaxCountPerStepToolRule

4 properties

JSON SCHEMA

MaxCountPerStepToolRuleSchema

3 properties

JSON SCHEMA

MCPServerSchema

6 properties

JSON SCHEMA

MCPServerType

0 properties

JSON SCHEMA

MCPTool

8 properties

JSON SCHEMA

MCPToolHealth

2 properties

JSON SCHEMA

Memory

5 properties

JSON SCHEMA

Message

25 properties

JSON SCHEMA

MessageCreate

8 properties

JSON SCHEMA

MessageRole

0 properties

JSON SCHEMA

MessageSearchCacheWarmScope

0 properties

JSON SCHEMA

MessageSearchRequest

10 properties

JSON SCHEMA

MessageSearchResult

5 properties

JSON SCHEMA

MessageType

0 properties

JSON SCHEMA

ModalSandboxConfig

4 properties

JSON SCHEMA

Model

31 properties

JSON SCHEMA

ModifyApprovalRequest

1 properties

JSON SCHEMA

ModifyFeedbackRequest

2 properties

JSON SCHEMA

NpmRequirement

2 properties

JSON SCHEMA

OmittedReasoningContent

2 properties

JSON SCHEMA

ChoiceLogprobs

2 properties

JSON SCHEMA

Function

2 properties

JSON SCHEMA

ChatCompletionTokenLogprob

4 properties

JSON SCHEMA

TopLogprob

3 properties

JSON SCHEMA

OpenAIModelSettings

7 properties

JSON SCHEMA

OpenAIReasoning

1 properties

JSON SCHEMA

OpenRouterModelSettings

5 properties

JSON SCHEMA

Organization

4 properties

JSON SCHEMA

OrganizationCreate

2 properties

JSON SCHEMA

OrganizationSourcesStats

4 properties

JSON SCHEMA

OrganizationUpdate

2 properties

JSON SCHEMA

PaginatedAgentFiles

3 properties

JSON SCHEMA

ParameterProperties

2 properties

JSON SCHEMA

ParametersSchema

3 properties

JSON SCHEMA

ParentToolRule

4 properties

JSON SCHEMA

Passage

15 properties

JSON SCHEMA

PassageBatchCreateRequest

1 properties

JSON SCHEMA

PassageCreateRequest

4 properties

JSON SCHEMA

PassageSearchRequest

8 properties

JSON SCHEMA

PassageSearchResult

3 properties

JSON SCHEMA

PipRequirement

2 properties

JSON SCHEMA

PromptTokensDetails

2 properties

JSON SCHEMA

Provider

13 properties

JSON SCHEMA

ProviderCategory

0 properties

JSON SCHEMA

ProviderCheck

6 properties

JSON SCHEMA

ProviderCreate

7 properties

JSON SCHEMA

ProviderTrace

17 properties

JSON SCHEMA

ProviderType

0 properties

JSON SCHEMA

ProviderUpdate

5 properties

JSON SCHEMA

ReasoningContent

4 properties

JSON SCHEMA

ReasoningMessage

13 properties

JSON SCHEMA

ReasoningMessageListResult

6 properties

JSON SCHEMA

RedactedReasoningContent

2 properties

JSON SCHEMA

RequiredBeforeExitToolRule

3 properties

JSON SCHEMA

RequiresApprovalToolRule

3 properties

JSON SCHEMA

ResetMessagesRequest

1 properties

JSON SCHEMA

RetrieveStreamRequest

7 properties

JSON SCHEMA

RoundRobinManager

2 properties

JSON SCHEMA

RoundRobinManagerUpdate

2 properties

JSON SCHEMA

Run

17 properties

JSON SCHEMA

RunMetrics

9 properties

JSON SCHEMA

RunStatus

0 properties

JSON SCHEMA

SandboxConfig

7 properties

JSON SCHEMA

SandboxConfigCreate

1 properties

JSON SCHEMA

SandboxConfigUpdate

1 properties

JSON SCHEMA

SandboxEnvironmentVariable

10 properties

JSON SCHEMA

SandboxEnvironmentVariableCreate

3 properties

JSON SCHEMA

SandboxEnvironmentVariableUpdate

3 properties

JSON SCHEMA

SandboxType

0 properties

JSON SCHEMA

SearchAllMessagesRequest

7 properties

JSON SCHEMA

SearchCacheWarmRequest

2 properties

JSON SCHEMA

SearchCacheWarmResponse

3 properties

JSON SCHEMA

SGLangModelSettings

8 properties

JSON SCHEMA

SkillSchema

3 properties

JSON SCHEMA

SleeptimeManager

3 properties

JSON SCHEMA

SleeptimeManagerSchema

3 properties

JSON SCHEMA

SleeptimeManagerUpdate

3 properties

JSON SCHEMA

Source

11 properties

JSON SCHEMA

SourceCreate

7 properties

JSON SCHEMA

SourceSchema

8 properties

JSON SCHEMA

SourceStats

5 properties

JSON SCHEMA

SourceUpdate

5 properties

JSON SCHEMA

SSEMCPServer

7 properties

JSON SCHEMA

SSEServerConfig

6 properties

JSON SCHEMA

StdioMCPServer

6 properties

JSON SCHEMA

StdioServerConfig

5 properties

JSON SCHEMA

Step

30 properties

JSON SCHEMA

StepMetrics

12 properties

JSON SCHEMA

StepStatus

0 properties

JSON SCHEMA

StopReasonType

0 properties

JSON SCHEMA

StreamableHTTPMCPServer

7 properties

JSON SCHEMA

StreamableHTTPServerConfig

6 properties

JSON SCHEMA

SummarizedReasoningContent

4 properties

JSON SCHEMA

SummarizedReasoningContentPart

2 properties

JSON SCHEMA

SummaryMessage

12 properties

JSON SCHEMA

SupervisorManager

2 properties

JSON SCHEMA

SupervisorManagerSchema

2 properties

JSON SCHEMA

SupervisorManagerUpdate

2 properties

JSON SCHEMA

SystemMessage

11 properties

JSON SCHEMA

SystemMessageListResult

6 properties

JSON SCHEMA

TagSchema

1 properties

JSON SCHEMA

TerminalToolRule

3 properties

JSON SCHEMA

TextContent

3 properties

JSON SCHEMA

TextResponseFormat

1 properties

JSON SCHEMA

TogetherModelSettings

5 properties

JSON SCHEMA

Tool

18 properties

JSON SCHEMA

ToolAnnotations

5 properties

JSON SCHEMA

ToolCall

3 properties

JSON SCHEMA

ToolCallContent

5 properties

JSON SCHEMA

ToolCallDelta

3 properties

JSON SCHEMA

ToolCallMessage

12 properties

JSON SCHEMA

ToolCallNode

2 properties

JSON SCHEMA

ToolCreate

11 properties

JSON SCHEMA

ToolEnvVarSchema

5 properties

JSON SCHEMA

ToolExecutionResult

6 properties

JSON SCHEMA

ToolJSONSchema

5 properties

JSON SCHEMA

ToolReturnContent

4 properties

JSON SCHEMA

ToolReturnCreate

4 properties

JSON SCHEMA

ToolReturnMessage

16 properties

JSON SCHEMA

ToolRunFromSource

9 properties

JSON SCHEMA

ToolSearchRequest

5 properties

JSON SCHEMA

ToolSearchResult

5 properties

JSON SCHEMA

ToolType

0 properties

JSON SCHEMA

ToolUpdate

12 properties

JSON SCHEMA

TurnTokenData

5 properties

JSON SCHEMA

UpdateAgent

37 properties

JSON SCHEMA

UpdateAssistantMessage

2 properties

JSON SCHEMA

UpdateConversation

4 properties

JSON SCHEMA

UpdateMCPServerRequest

2 properties

JSON SCHEMA

UpdateReasoningMessage

2 properties

JSON SCHEMA

UpdateSystemMessage

2 properties

JSON SCHEMA

UpdateUserMessage

2 properties

JSON SCHEMA

UrlImage

2 properties

JSON SCHEMA

UsageStatistics

5 properties

JSON SCHEMA

UsageStatisticsCompletionTokenDetails

1 properties

JSON SCHEMA

UsageStatisticsPromptTokenDetails

3 properties

JSON SCHEMA

User

5 properties

JSON SCHEMA

UserCreate

1 properties

JSON SCHEMA

UserMessage

11 properties

JSON SCHEMA

UserMessageListResult

6 properties

JSON SCHEMA

UserUpdate

2 properties

JSON SCHEMA

ValidationError

3 properties

JSON SCHEMA

VectorDBProvider

0 properties

JSON SCHEMA

VoiceSleeptimeManager

4 properties

JSON SCHEMA

VoiceSleeptimeManagerSchema

4 properties

JSON SCHEMA

VoiceSleeptimeManagerUpdate

4 properties

JSON SCHEMA

XAIModelSettings

5 properties

JSON SCHEMA

ZAIModelSettings

6 properties

JSON SCHEMA

ZAIThinking

2 properties

JSON SCHEMA

Scroll within the panel for all 349 ·

JSON Structure 15

JSON Structure captures the data shapes in a form built for tooling — a complement to JSON Schema that keeps the model machine-legible.

JSON Structure definitions describing this provider's data shapes.

Letta Agent Structure

0 properties

JSON STRUCTURE

Letta Archive Structure

0 properties

JSON STRUCTURE

Letta Block Structure

0 properties

JSON STRUCTURE

Letta Embedding Config Structure

0 properties

JSON STRUCTURE

Letta Group Structure

0 properties

JSON STRUCTURE

Letta Identity Structure

0 properties

JSON STRUCTURE

Letta Job Structure

0 properties

JSON STRUCTURE

Letta Llm Config Structure

0 properties

JSON STRUCTURE

Letta Message Structure

0 properties

JSON STRUCTURE

Letta Passage Structure

0 properties

JSON STRUCTURE

Letta Provider Structure

0 properties

JSON STRUCTURE

Letta Run Structure

0 properties

JSON STRUCTURE

Letta Source Structure

0 properties

JSON STRUCTURE

Letta Structure

0 properties

JSON STRUCTURE

Letta Tool Structure

0 properties

JSON STRUCTURE

Scroll within the panel for all 15 ·

Examples 29

Real request and response payloads are what turn a spec from abstract into obvious — and they're one of the twelve things an agent needs to call an API correctly on the first try.

Example request and response payloads for these APIs.

Scroll within the panel for all 29 ·

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Letta Authentication

http · 1 scheme

SECURITY

Letta Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.

Recommended x-agentic-access execution contracts for AI agents.

Letta Agentic Access

604 operations · 346 acting · 8 human-in-the-loop

604 operations · 346 acting

AGENTIC

Resources

Every other property we hold for Letta — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.

Get Started 1

Portal, sign-up, and the first successful call

Documentation 1

Reference material describing how the API behaves

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

Design & Contract 3

Pagination, idempotency, versioning, errors, and events

Build 4

SDKs, sample code, and the tooling you integrate with

Access & Security 2

Authentication, authorization, and security posture

Operate 1

Status, limits, changes, and where to get help

Commercial 3

Pricing, plans, and the legal terms of use

Company 3

The organization behind the API

Other 1

Properties that don't map to a standard resource type

← All providers · Data indexed from github.com/api-evangelist/letta · machine-readable index on apis.io