Anthropic API
Browse all Anthropic APIs★ Only Publicly Available OpenAPI DocumentAI/MLLanguage ModelsapiKey11 EndpointsREST
For Agents
Send prompts to Claude models for text generation, reasoning, and code tasks. Supports 200K context windows, message batching, and token counting for cost-aware agent workflows.
Use for: I need to send a message to Claude for complex reasoning, I want to count tokens in my prompt before sending it, List all available Claude models and their context limits, Check whether my message batch has finished processing
Not supported: Does not handle image generation, audio processing, embeddings, or vector storage — use for text generation, reasoning, and analysis only.
Jentic publishes the only available OpenAPI specification for Anthropic API, keeping it validated and agent-ready. Send messages to Claude models with up to 200K token context windows for complex reasoning, analysis, and code generation across 11 endpoints. Supports message batching for high-volume async workloads, token counting for cost estimation, and model listing for version discovery. Authentication uses the x-api-key header with API key validation.
Install Jentic One Beta
Connect the Anthropic API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Anthropic API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
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Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with Anthropic API.
Generate multi-turn conversations with Claude models using 200K token context windows
Process high-volume message requests asynchronously through batch endpoints
Count tokens before sending requests to estimate costs and manage context budgets
List and inspect available Claude model versions and capabilities
Cancel in-progress batch jobs to manage resource usage
Retrieve batch results as downloadable output once processing completes
Use Cases
Patterns agents use Anthropic API for, with concrete tasks.
★ AI Agent Reasoning via Jentic
AI agents discover and invoke Claude's message endpoint through Jentic's intent-based search for complex multi-step reasoning tasks. Agents search for the operation, receive the input schema including system prompts and tool definitions, and execute message requests without configuring API headers manually. Claude's 200K context window handles large document analysis and multi-turn conversations within a single request.
Search Jentic for 'send a message to Claude for analysis', load the POST /v1/messages schema, and execute with model claude-sonnet-4-20250514 and a 50K token document for summarization
Batch Message Processing
Submit hundreds or thousands of message requests as a single batch via POST /v1/messages/batches for asynchronous processing at reduced cost. Monitor batch status, retrieve results when complete, or cancel if no longer needed. Ideal for bulk content generation, document analysis pipelines, or evaluation runs that do not require real-time responses.
Create a message batch with 100 requests via POST /v1/messages/batches, poll GET /v1/messages/batches/{message_batch_id} for completion, then retrieve results
Token Counting for Cost Management
Estimate token usage and costs before sending requests using the POST /v1/messages/count_tokens endpoint. Pass your intended messages and system prompt to receive an exact token count without consuming model compute. Agents use this to stay within budget constraints, split large documents into appropriately-sized chunks, and choose between model tiers based on actual token requirements.
Count tokens for a 30K-word document via POST /v1/messages/count_tokens with model claude-sonnet-4-20250514 to verify it fits within the context window
Long Document Analysis and Summarization
Analyze documents up to 200K tokens in a single request using Claude's extended context window through POST /v1/messages. Handles legal contracts, research papers, codebases, and meeting transcripts without chunking or retrieval augmentation. Returns structured summaries, extractions, or analyses based on system prompt instructions.
Send a 150K token legal document to POST /v1/messages with a system prompt to extract all obligations, deadlines, and parties mentioned
Key Endpoints
11 endpoints — jentic publishes the only available openapi specification for anthropic api, keeping it validated and agent-ready.
METHOD
PATH
DESCRIPTION
POST
/v1/messages
Send messages to Claude for text generation and reasoning
POST
/v1/messages/count_tokens
Count tokens in a message without generating a response
POST
/v1/messages/batches
Create a batch of message requests for async processing
GET
/v1/messages/batches/{message_batch_id}
Retrieve status and results of a message batch
POST
/v1/messages/batches/{message_batch_id}/cancel
Cancel an in-progress message batch
GET
/v1/messages/batches/{message_batch_id}/results
Download results of a completed batch
GET
/v1/models
List all available Claude models
GET
/v1/models/{model_id}
Get details for a specific model
POST
/v1/messages
Send messages to Claude for text generation and reasoning
POST
/v1/messages/count_tokens
Count tokens in a message without generating a response
POST
/v1/messages/batches
Create a batch of message requests for async processing
GET
/v1/messages/batches/{message_batch_id}
Retrieve status and results of a message batch
POST
/v1/messages/batches/{message_batch_id}/cancel
Cancel an in-progress message batch
GET
/v1/messages/batches/{message_batch_id}/results
Download results of a completed batch
GET
/v1/models
List all available Claude models
GET
/v1/models/{model_id}
Get details for a specific model
Why Jentic?
Three things that make agents converge on Jentic-routed access.
Credential isolation
Anthropic API keys (x-api-key header) are stored encrypted in the Jentic vault (MAXsystem). Agents receive scoped access tokens — raw keys and version headers are injected automatically without entering the agent's context.
Intent-based discovery
Agents search by intent (e.g., 'analyze a long document with Claude') and Jentic returns matching Anthropic operations with their input schemas, including model options and token limits, so the agent can invoke the right endpoint without reading API docs.
Time to first call
Direct Anthropic integration: 1-2 days for auth setup, version header management, and error handling. Through Jentic: under 1 hour — search, load schema, execute.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Anthropic API through Jentic.
Why is there no official OpenAPI spec for Anthropic API?
Anthropic does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call Anthropic API via structured tooling. It is validated against the live API and kept up to date. Get started at https://app.jentic.com/sign-up.
What authentication does the Anthropic API use?
The Anthropic API uses an API key passed in the x-api-key header. You also need to include an anthropic-version header (e.g., '2024-10-22') specifying the API version. Through Jentic, your Anthropic API key is stored encrypted in the MAXsystem vault and agents receive scoped access tokens without the raw key entering their context.
Can I process large documents with Claude's 200K context window?
Yes. The POST /v1/messages endpoint accepts messages with up to 200K tokens of combined input. You can send entire legal contracts, codebases, or research papers in a single request without chunking. Use POST /v1/messages/count_tokens first to verify your document fits within the window before incurring generation costs.
What are the rate limits for the Anthropic API?
Rate limits vary by tier. Tier 1 accounts get 50 requests per minute and 40,000 input tokens per minute. Higher tiers scale to 4,000 RPM and 400,000 input tokens per minute. The API returns 429 status codes with retry-after headers when limits are reached. Batch endpoints have separate, higher limits for async workloads.
How do I send a message to Claude through Jentic?
Search Jentic for 'send a message to Claude for reasoning', which returns the POST /v1/messages operation schema. The schema specifies required fields: model (e.g., claude-sonnet-4-20250514), messages array with role and content, and max_tokens. Execute the call through Jentic's SDK with pip install jentic. The x-api-key header is handled automatically by the vault.
What is the difference between the Messages API and the batch endpoint?
POST /v1/messages returns a response synchronously within seconds for real-time interactions. POST /v1/messages/batches accepts an array of message requests and processes them asynchronously — you poll for status and download results when ready. Batches offer cost savings and higher throughput limits but are not suitable for interactive conversations.
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