Download File

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

Annotations already cover the read-only, idempotent, non-destructive profile, and the description usefully adds the return payload (saved path and size). It says nothing about overwrite behavior if the file already exists in dest_dir, permission/auth needs, or whether the local write is a side effect of a readOnly tool.

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 short sentences, front-loaded with the action, then the return value, then the prerequisite lookup. No 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?

With no output schema, stating the returned path and size is valuable, and the two-parameter surface is fully covered by schema. Only the local-file collision/overwrite behavior is missing for a disk-writing tool.

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 both file_id and dest_dir are already documented, including the CANVAS_DOWNLOAD_DIR default. The description only reinforces where file_id comes from and does not add semantics for dest_dir or file_id format.

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?

The description gives a specific verb and resource — download one Canvas file and save it to local disk — plus a concrete side effect (saved path and size).

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?

"Get file_id from list_course_files or list_my_files" is prerequisite guidance, but the description never states when to prefer this over the sibling bulk/attachment downloaders (download_all_course_files, download_submission_attachment, download_media_captions), so usage is only implied.

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