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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds substantial context beyond them: signed-in requirement, no side effects, the state machine (queued|rendering|ready|failed), the billing rule that nothing is charged until unlock_job, and the 'No such job' error for ids outside the account.

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?

Dense but front-loaded: the core behavior leads, followed by usage cadence, then return shape and error/related-tool notes. It is longer than typical, though nearly every clause carries operational value (polling interval, billing rule, credits_cost caveat).

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?

There is no output schema, and the description fully specifies the return shape for both modes, including field names and the credits_cost/credits_cost_known dependency. An agent has everything needed to call and interpret this tool without guessing.

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 schema already documents job_id, but the description adds real meaning: omitting it returns the ten most recent jobs, and an id must belong to this account or the call errors. That goes beyond the schema's UUID format description.

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?

States a precise verb+resource (get one job by id, or the ten most recent), including the distinct two-mode behavior in the first sentence. It is clearly distinguishable from siblings like create_media_job, unlock_job, and get_downloads, which it names as different responsibilities.

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?

Gives explicit when-to-use guidance (poll after create_media_job, every 10-20 seconds, up to 10 minutes, until state is ready or failed) and what to do past that window. It also names the alternative tools for adjacent needs: get_downloads for files and estimate_media_job for pricing before upload.

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