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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description's 'Read-only' is consistent with rather than contradicting them. It adds real behavioral value beyond the annotations by disclosing the state machine and what payload accompanies each terminal state. Polling cadence, whether jobs expire, or how long a url remains valid are not covered.

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?

One tight sentence that front-loads the resource and then enumerates states in a scannable slash-delimited list. Zero filler; every clause carries information an agent needs.

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?

No output schema exists, and the description compensates well by spelling out the return shape per status (url on completed, error on failed). What remains thin is operational context such as whether the caller should poll and how often, which matters for a status-check 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 description coverage is 100% and the single jobId parameter is documented in the schema as coming from add_captions, so the description need not repeat it. It adds no format, lifetime, or validity semantics for jobId. 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?

Specific verb+resource ('State of an add_captions render') with the full status vocabulary enumerated, including what each terminal state carries (url on completed, error on failed). An agent can distinguish this from get_post_status or check_media_upload purely from the description.

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?

Implicitly situates the call after add_captions via 'an add_captions render' and jobId linkage, and gives an explicit next step for the completed case (url 'ready for create_post'). It stops short of naming when not to use it or what to do instead for non-caption jobs.

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