Get a render

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description goes beyond these by adding that the call is free, that an unknown id returns an error, and that download URLs expire. This gives the agent useful operational context beyond the structured annotations.

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

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

The description is front-loaded with the core purpose, then usage guidance, then behavioral notes. Every sentence earns its place and the whole thing remains compact despite covering return fields, polling, expiry, alternatives, and error behavior.

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

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

Since there is no output schema, the description carries the burden of explaining the return value, and it does so thoroughly by listing status values and response fields. It also covers why the tool exists, when alternatives are preferable, cost, and error behavior, which is complete for a simple read-only lookup tool.

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

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

Schema coverage is 100%, so the id parameter is already documented. The description adds value by clarifying that the id comes from a render or convert_to_pdf call and by exposing the unknown-id error behavior, which the schema does not state.

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

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

The description opens with a specific verb and resource: 'Returns the current state of a render', and enumerates the exact fields returned (status, download_url, expires_at, page_count, units, error). It distinguishes itself from siblings by noting render and convert_to_pdf already return this information for a just-created render.

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

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

Explicitly states when to use this tool: to follow a render started with wait false, or to refresh an expired download link. It also names alternatives and their relationship: render and convert_to_pdf already return the same data for the render they just made, so this tool is for later or renewed access.

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