canvas_discussion

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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds the non-obvious side effect that reading does not mark the topic read, plus the shape of the returned content — genuine value beyond the structured fields.

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 the core action and return content, followed by the side effect and the sibling pointer. Nothing is wasted and no sentence is redundant.

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 read-only single-resource fetch with full schema coverage and annotations, the description covers purpose, return content, side effects, and reply routing. The only omission is pagination behavior for the page parameter, which the schema handles but the description does not reinforce.

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 all five parameters (raw, page, topic_id, context_id, context_type) are already documented in the schema. The description adds no extra parameter meaning such as id provenance or pagination behavior, so the baseline of 3 applies.

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 ('Read one discussion topic or announcement in full') and enumerates what comes back (message text with links, author, dates). It is clearly distinguishable from the sibling list tool canvas_discussions and the reply tool canvas_discussion_entries.

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?

Explicitly routes reply-reading to canvas_discussion_entries, and the schema's topic_id description points at canvas_discussions or canvas_announcements as the source of ids. It stops short of an explicit 'use this instead of canvas_discussions when...' contrast, so it is clear context rather than full exclusions.

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