canvas_open_item

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the description is not obligated to cover safety. It still adds real behavioral detail: module IDs vs page slugs, that module opens return paginated items even when Canvas omitted inline items, that module items resolve to their target with prerequisites, lock/completion state, external links, and sequence navigation preserved, and the important side-effect guarantee that reading never marks a module complete or starts a quiz. The limit/offset/refresh behavior (caching) is left unexplained, keeping it below a 5.

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 description is short and front-loads the resource list before the caveats, with each sentence carrying a distinct fact (identity source, pagination fallback, target resolution, side-effect guarantee). Only the vague 'use identities returned by navigation' phrase is filler that could be tightened.

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?

Because an output schema exists, the description need not explain return shapes, and the behavioral notes cover the trickiest resolution cases. Still, for a 7-parameter tool with zero schema coverage, the absence of any explanation for limit, offset, refresh, and module_id leaves an agent guessing on pagination and cache behavior.

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 0%, so the description must carry parameter meaning, and it only partially does. It clarifies that item_id may be a slug for pages and that module_id relates to module items implicitly, but limit, offset, and refresh — including the non-obvious caching implication of refresh — are never mentioned, and module_id is never explained.

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 opening sentence gives a concrete verb (open) and enumerates the exact resource types it handles (module, module item, page, assignment, file, quiz, discussion), which lets an agent match it to a request quickly. It stops short of differentiating itself from overlapping siblings like get_assignment, get_file, or canvas_browse_course, so the boundary is inferred rather than stated.

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?

'Use identities returned by navigation' gives a provenance hint for where the IDs come from, which is genuine usage context. However, there is no explicit when-to-use-this-vs-sibling guidance, no mention of when to prefer get_assignment or list_modules, and no stated prerequisites or error conditions.

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