justcaptions

cancel_job

Stop a specified job by ID to halt local rendering and pending files; an in-flight cloud request may still finish and be charged, with its response cached for resume.

Instructions

Stop owned local rendering and pending files. An in-flight cloud request may finish and be charged; its response is cached for resume.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "job_id": "<job_id>"
    },
    "name": "cancel_job"
  }
}

Input Schema

Name	Required	Description	Default
`job_id`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.4.0Oct 7, 2026

TDQS

A3.6/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only state the safety profile (readOnly/destructive/idempotent hints), whereas the description adds genuinely non-derivable behavior: an in-flight cloud request may still complete and be charged, and its response is cached for later resume. That cost/irreversibility context is exactly what an agent needs and is not in the structured fields.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences, with the scope/action front-loaded and the cost caveat second. Every clause carries information; there is no padding or restatement of the title.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The output schema is present so return values need not be described, and the description covers the key caveats (partial cancellation, billing, resume caching). The remaining gap is the undocumented job_id and idempotency expectation, minor against an otherwise complete cancel tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There is one required parameter (job_id) with 0% schema description coverage, so the description carries the full burden, yet it never explains what job_id is or where to obtain it. The name is fairly self-evident, but the description adds no meaning beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The verb 'Stop' plus the resource ('owned local rendering and pending files') makes the cancel intent clear, and the mention of an in-flight cloud request distinguishes behavior from a plain list/get job tool. It never uses the word 'cancel' or the job_id, so the mapping to the tool name is inferred rather than stated, keeping it just under 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied: stopping work that is 'owned' and cannot be fully recalled on the cloud side. The cache-for-resume note hints that resume_job is the follow-up path, but no explicit when-to-use or when-not-to-use condition is given, and siblings like resume_job/get_job are not named.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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