post_v1_tools_call

CallTool runs one of the caller's activated tools and answers with its output.

This is the door onto the tool plane's DYNAMIC half — the half no build-time catalogue can hold, because it is per-tenant: an org's connected connector actions, its authored skills, its agents and functions, and the tools of every external MCP server it registered. A tool's existence, its price and its activation are all rows, not code, so they cannot be known until the caller is.

One policy, the registry's: resolve by precedence, refuse an unactivated tool 403, settle a priced one through the x402 seam or fail closed 402, then dispatch to the winning source bound to the caller's own (org, project). One metered unit, one audit record. A caller can only ever dispatch its own tools.

Discovery is GET /v1/tools — ?activated=true for the callable set.

Arguments

tools/list declares a type and a description for each field and nothing further. A — means neither the door nor that operation constrains the field.

Call it

A tools/call carries every argument in one flat object — nothing binds to a path or a query string. Nothing above is required, so every declared argument is shown rather than a guess at which matter.

curl -X POST https://api.hanzo.ai/v1/mcp \
  -H "Authorization: Bearer $HANZO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "tools/call",
       "params": {
         "name": "post_v1_tools_call",
         "arguments": {
           "arguments": {},
           "name": "<name>"
         }
       }
     }'

Values are the operation's own defaults and enumerated values where it declares them, and a <placeholder> where neither source declares one. tools/list needs no credential; tools/call does — called without one the door answers HTTP 200 with a JSON-RPC result whose isError is set and whose text says what was missing. How to get a key →

The operation behind it

The same capability over plain HTTP is in the tools API reference, on https://api.hanzo.ai.

All 755 tools · The door · API reference

Generated from tools/list on https://api.hanzo.ai/v1/mcp — 833 tools captured 2026-08-01, of which 755 are documented here (the operator surface is not published) (this build read the vendored copy; the door was unreachable).