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

Beyond the readOnlyHint annotation, the description discloses important behavior: a job whose invocation died is reported as 'failed' rather than remaining 'running' forever. This tells the agent that polling will eventually terminate, which is valuable behavioral context not available from annotations alone.

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 exceptionally concise: two sentences that state the tool's purpose, return values, and failure semantics. Every sentence adds essential information, and the most important usage detail is front-loaded.

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 simple one-parameter polling tool with readOnlyHint and no output schema, this description covers everything needed: what it checks, what states are returned, and how failures are handled. No critical information is missing.

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?

The schema already fully describes the single required parameter, job_id, as 'The job id from start_background_job.' The description reinforces this by referring to jobs started with start_background_job, but does not add significant new meaning beyond the schema. Baseline 3 is appropriate given 100% schema coverage.

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 clearly states the tool's purpose: checking a background job started with start_background_job. It specifies the resource (background job) and the action (check), and defines the possible return states. This differentiates it from sibling tools like start_background_job and get_scale_job.

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 provides clear usage context: it is meant for checking jobs created by start_background_job and is safe to poll until the status stops being 'running'. It implies the polling pattern without explicitly listing alternatives or exclusions, but the guidance is sufficient for correct use.

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