> ## Documentation Index
> Fetch the complete documentation index at: https://docs.guidinghand.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Http tool call

> When an agent calls one of its HTTP tools (`tools.http`), GuidingHand POSTs the call to the tool’s `url` with a `GuidingHand-Signature: t=<unix>,v1=<hex>` header: the HMAC-SHA256 of `<t>.<raw body>` with your org’s tool secret (`GET /v1/tool_secret`), as for webhook events. It waits up to 15 seconds, follows no redirects and makes each call once. Your response body, as text (up to 64 KB), is what the model gets back: a 2xx is the result, and any other status, or no answer, tells the model the call failed. A tool with `approval: "always"` is only called once someone approves.



## OpenAPI

````yaml /api-reference/openapi.json webhook tool_call
openapi: 3.1.0
info:
  title: GuidingHand API
  version: 1.0.0
  description: >-
    Create sessions (an invite link with a code for the person at the computer),
    run tasks on their computer with one of your agents, follow them, answer
    their questions and approvals, and fetch history and recordings. Test your
    agents with evals: test cases on fresh machines, run in test sets, scored by
    a check script or a rubric. Agents are versioned (save a draft, publish it),
    have tools (their own file system, and your HTTP endpoints), and every
    change is in the org’s audit log.
servers:
  - url: https://guidinghand.ai
    description: Production
  - url: https://dev.guidinghand.ai
    description: Development (Stripe test mode)
security:
  - bearerAuth: []
tags:
  - name: Agents
  - name: Agent files
  - name: Agent tools
  - name: Sessions
  - name: Tasks
  - name: Webhooks
  - name: Audit log
  - name: Test cases
  - name: Test sets
  - name: Test runs
  - name: Start states
  - name: Runners
paths: {}
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: An org API key (`gh_live_…`) from Settings → API keys in the console.

````