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

Annotations only supply destructiveHint=false; the description carries the real behavioral burden and does so well, disclosing the two-phase flow (get upload_url, PUT the bytes to it) that is not visible anywhere in the schema or annotations. It omits operational details such as upload_url expiry, auth requirements, or POST-vs-PUT content expectations.

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?

Two short sentences, zero filler, and the sequence of actions is front-loaded in the order the agent must execute them. Every clause earns its place.

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?

With no output schema, the description usefully states what comes back (upload_url) and what to do with it, and the schema covers all inputs. The remaining gap is lifecycle detail — how long the URL is valid, whether robot_key must be carried forward — which a first-time caller would benefit from.

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%, so all 10 parameters already carry their own documentation (model default, robot_key chaining, size limit, ISO language codes). The description adds no parameter-level meaning beyond the schema, so the 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?

States a specific resource (upload) and outcome (returns an upload_url) plus the exact follow-up call (start_transcription). The phrase "For a file on your machine" implicitly scopes it against URL-sourced siblings like transcribe_url, so an agent can route correctly without opening a schema.

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 a clear triggering condition (a local file) and names the next step explicitly ("then call start_transcription"). It does not, however, name the alternative to use when the media is not on the machine (e.g., transcribe_url), so the routing is implied rather than fully spelled out.

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