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

Beyond the readOnlyHint annotation, the description adds meaningful behavior: signed URLs are short-lived while the stored object persists, the tool is free, and it never re-renders. This clarifies side-effect expectations without contradicting the 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?

Three sentences carry the purpose, usage scenarios, and behavioral caveats with no filler. The core action is front-loaded and every remaining clause adds decision-relevant information.

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?

With no output schema, the description still names the return content (status and freshly signed URL) and the two main calling scenarios. It does not enumerate possible status values or error behavior, but for a one-parameter read-only tool this is a minor gap.

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%, and the input schema already documents render_id with an example and the note that it comes from a previous render call. The tool description only adds 'by id', so it provides no meaningful semantic value beyond the schema; baseline 3 applies.

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 states a specific verb and resource: 'Fetch a render by id.' It also names the exact outputs (status and a freshly signed URL), so an agent can distinguish this from sibling tools like render, list_renders, or get_template.

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?

The description gives two explicit use cases: polling a queued render and re-signing an expired URL. It does not explicitly name alternatives or say when not to use it, so it stops short of a full when/when-not guide.

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