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

With readOnlyHint=true already covering safety, the description adds genuine behavioral context: it discloses the returned fields (state, progress) and the conditional nature of the download URL, which only appears once the job finishes. This is the key behavior an agent needs to avoid misinterpreting an incomplete response, though polling cadence or terminal-state semantics are not addressed.

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?

A single front-loaded sentence with no filler; the returned fields are ordered by when they become available, which is efficient and readable.

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 one-parameter, read-only tool with no output schema, the description adequately covers what comes back and under what condition. Minor gaps remain around job state values and behavior for an invalid or expired job id, but nothing essential to invoking it correctly 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?

Schema coverage is 100% and the single job_id parameter is already documented as 'Job id returned by create_reel', so the schema carries the semantic load. The description adds no parameter-level detail beyond that, making the baseline 3 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?

States a specific verb ('Read') and resource ('reel job'), and even names the data returned (state, progress, download URL), so an agent knows exactly what it retrieves. It does not explicitly contrast itself with siblings, but its scope is distinct enough from create_reel or get_performance to be unambiguous.

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?

There is no explicit 'use when' statement, but the phrase 'once finished, its download URL' implies polling a job until completion, which is a usable usage signal. The schema's 'Job id returned by create_reel' reinforces the workflow, yet the description itself never routes the agent or states preconditions.

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