CasusLegal connector in your product

1. Connection

Standard MCP server: connect it like any other connector in your chat.

curl -sS https://mcp.casus.legal/partner/mcp \
  -H "Authorization: Bearer $CASUS_PARTNER_KEY" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{
        "protocolVersion":"2025-06-18","capabilities":{},
        "clientInfo":{"name":"my-platform","version":"1.0"}}}'

The response contains — serverInfo.name: "CasusLegal Partner". Next, tools/list it should return nine tools.

2. Request headers

X-Partner-User-Id — any stable string that does not reveal the person’s identity: your internal identifier or its hash. It serves two purposes.

• Limits are calculated per user, not for the platform as a whole. There is one key, and without this header all your lawyers share one bucket: one client stuck in a loop hits the ceiling, while the others receive refusals.
• Per-user itemized accounting. We use it to reconcile our figures with yours: how many calls, of what types, and how many people actually reached the connector.

3. Tools

Six tools, each with a parameter corpus.

Parameter corpus

{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{
  "name":"casuslegal_search_practice",
  "arguments":{
    "query":"recovery of a penalty, reduction under Article 333 of the Civil Code",
    "corpus":"main",
    "limit":10
  }}}

4. What the response contains

A structured object. For the main corpus, these are the blocks constitutional_context (legal positions of the Constitutional Court of the Russian Federation), vs_guidance (Plenum resolutions and reviews of the Supreme Court of the Russian Federation), latest_practice (recent rulings of judicial chambers), vas_history (practice of the Supreme Commercial Court of the Russian Federation) and results.

Volume

One search returns approximately 110,000 characters, or about 40,000 tokens as input to your model. This is intentional: completeness of the results is the product. Factor this volume into your choice of the model that processes the response — at this scale, the difference in cost between models can be as much as twelvefold.

Time

A search takes about 30 seconds. Set the tool-call timeout to at least 120 seconds; otherwise, you will interrupt requests that are proceeding normally.

Links to judicial acts

Each judicial act has a field url — a page containing the full text. Pass it to the user as is, and do not truncate the parameter ?t=: without it, the link is invalid. The link remains valid for 30 days. If you plan to embed links in client documents, tell us — we will make them permanent.

Full text

The search returns the identifying details and key excerpts; the full judicial act is obtained by a separate call casuslegal_get_case_details(case_id, corpus). case_id is valid only within its own corpus.

5. Errors and limits

Failures are returned as a successful tool response with a field error — this allows your model to explain the situation to the user, rather than treating the connector as broken.

401 is returned only at the connection level: the key is incorrect, revoked or expired. This is a configuration error; retries will not resolve it.

Default limits

• 20,000 calls per hour per integration;
• 400 calls per hour per end user;
• 24 concurrent searches per integration, 4 per user;
• a daily cap on the number of distinct judicial acts — protecting the corpus from mass downloading.

Limits can be adjusted: if you reach one during normal operation, let us know and we will raise it.

6. Pre-launch checklist

• Transport — streamable HTTP, not SSE.
• tools/list returns nine tools.
• Tool-call timeout — at least 120 seconds.
• Header X-Partner-User-Id is set on every call.
• corpus is selected based on the subject of the question, one corpus per request.
• Links url reach the user in full, together with ?t=.
• The model processing the results has been selected with 40,000 tokens per search in mind.
• Field error in the tool response is processed and shown to the user.