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

Adds substantial context the annotations do not carry: the 1.5 MB inline cap, the 25 MB ceiling via files_upload_link, the 1 GB free quota, per-call cost ($0.001) and no charge on failure, and that duplicates are kept rather than rejected. Annotations only say readOnly=false, destructive=false, idempotent=false, so this is real added value. The one blemish is that 'duplicate_of' is mentioned with no indication that it is a response field rather than an input, which reads as a phantom parameter against a schema that forbids additional properties.

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?

The purpose and the exclusivity rule are front-loaded in the first two sentences, which is exactly right. The third sentence is a dense, fragment-heavy routing list and the trailing duplicate_of/cost sentence is compressed to the point of ambiguity, but no sentence is pure filler.

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 mutation tool with no output schema, the description covers what an agent needs: size limits, expiry of the returned link, quota, cost, duplicate behaviour, and where to go for larger files or alternative sources. Nothing material 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?

Beyond the 67%-covered schema, the description supplies the critical semantics the schema cannot express: mutual exclusivity of content_base64/text/url and the 1.5 MB practical limit on base64 content. It also clarifies that url must be a public https link that the server fetches, which sharpens the schema's bare 'A public https:// link to the file.' It does not explain link_hours or content_type, but those are already described in the schema.

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 and resource ('Store a file in the account's private file store') plus the outcome ('get a download link'), which tells the agent exactly what it gets back. The final sentence of the first block implicitly distinguishes it from files_upload_link by scope (1.5 MB inline vs. larger), so an agent can tell the two apart without opening schemas.

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 an explicit exclusivity rule ('Give exactly one of: content_base64, text, or url') with per-branch guidance on which to pick. It also routes the agent away from this tool in concrete cases: larger files to files_upload_link, a person's own document to files_upload_link's page_url, a document you write to documents_create_pdf. This is the when/when-not/alternatives bar met in full.

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