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

The description adds rich behavioral context beyond annotations: the return format with status field and conditional fields, typical timing, and explicitly states 'Read-only and spends no quota', which aligns with readOnlyHint=true and destructiveHint=false 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?

Four sentences, all essential: purpose, response format, polling guidance, and alternative for expired URL. Front-loaded with main purpose. No fluff.

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?

For a tool with one parameter, full schema coverage, good annotations, and no output schema, the description comprehensively covers its behavior, response shape, and relationship to sibling tools. Perfectly adequate.

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% with a single parameter 'job_id' described as 'The jobId render_async returned.' The description mentions jobId in return format but adds no new semantics beyond the schema. Baseline 3 is appropriate.

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 'Poll an asynchronous render job started by render_async', which is a specific verb (poll) and resource (render job). It clearly distinguishes from sibling tools like 'render_async' (starts job) and 'get_render' (gets fresh URL).

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 explicitly says when to use the tool (poll jobs started by render_async), provides polling frequency advice ('every few seconds rather than tight loop'), and names an alternative ('pass its render id to get_render for a fresh one') for expired URLs.

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