canvas_file

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds that the payload includes a Canvas-provided download URL, which is useful, but says nothing about the pagination semantics implied by the page parameter or whether the URL expires.

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, front-loaded with what the tool returns and immediately followed by the alternative. Nothing is wasted or restated from the schema.

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 correctly states what comes back (metadata plus download URL), and annotations cover safety. The remaining gap is minor: the sibling set contains several file-related tools and the description resolves only one of those collisions.

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% and every property (file_id, page, raw) carries its own documentation including the next_page bookmark convention. The description adds no meaning beyond the schema, which is the baseline-3 case.

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?

Names a specific verb+resource ('Read file metadata and its Canvas-provided download URL') and explicitly delegates text extraction to file_content. It stops short of distinguishing itself from the sibling canvas_file_download_link, which also deals with download URLs, so an agent still has to guess between those two.

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 gives one concrete routing rule: use file_content for extracting supported text. That is real when-to-use guidance against a close alternative, but there is no exclusion or guidance for canvas_file_download_link, canvas_file_original, or canvas_module_file.

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