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

Annotations declare readOnlyHint=false and destructiveHint=false, so the mutation profile is already known. The description adds real context beyond that: it returns a one-time AMT link, the user performs the upload/fill out-of-band, and 'the file never passes through the chat' discloses a privacy/data-flow trait. It does not mention auth or rate limits, but the human-in-the-loop handoff is valuable behavioral disclosure.

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?

Three sentences, front-loaded with the core action, then the handoff mechanics and the privacy note. No filler, though the middle sentence packs several sub-steps into one clause.

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 carries return-value burden and does so by explaining the one-time AMT link result. For a single-parameter initiation tool this is nearly complete; only explicit routing to the follow-up siblings (fill_status, read_fill_results) 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?

Only one parameter (model_id) with 100% schema description coverage, so the schema already documents it fully ('The model id, from list_models'). The description's phrase 'the model's categories' adds slight contextual meaning but no syntax beyond the schema, matching the baseline 3.

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+resource: 'Fill a spreadsheet with the model's categories.' An agent can tell this initiates a filling operation, though it doesn't explicitly contrast itself with siblings like fill_status or read_fill_results.

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 conveys the workflow context (a one-time AMT link, the user uploads and starts the fill themselves), which implies this is an initiation step. However, it never names alternatives such as fill_status or read_fill_results to route the agent among the fill-related siblings.

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