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

Goes well beyond the annotations by disclosing allowed MIME types, the 10 MB cap, a 60-calls-per-hour-per-workspace rate limit that explicitly counts refused files, and that source_url fetches do not follow redirects. The annotations already flag non-read-only/non-idempotent, and the description adds the operational constraints an agent needs to avoid failures.

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?

Front-loaded with purpose and return values, then tight supporting sentences on argument modes, accepted types/size, and rate limits. Every clause carries information an agent would otherwise have to discover by failing a call.

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 write tool with four optional parameters, the description covers invocation modes, constraints, and cost/limit behavior, and an output schema exists to document return shape. Nothing material is missing for correct invocation.

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%, so the baseline is 3, but the description adds genuine semantics the schema cannot express: the mutual exclusivity of source_url / base64+filename / upload_id. It also reinforces that filename is optional-but-recommended with upload_id, matching the schema's note about losing capitals and spaces.

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 this workspace') plus the concrete outputs (suggested_markdown, file_id), which tells an agent exactly what this does and what it gets back. It also implicitly positions itself against sibling create-upload-url by describing the upload_id handoff, so the agent can tell the two apart.

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?

'Pass exactly one of: source_url, base64 with filename, or upload_id from create-upload-url' gives clear mode-selection guidance and names the prerequisite sibling tool. It stops short of explicit when-not-to-use guidance (e.g., what to do if the file exceeds 10 MB or is a disallowed type), so it is clear context rather than full when/when-not coverage.

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