canvas_message_students

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

No annotations exist, so the description carries the full burden and does so well: it discloses irreversibility ('cannot be recalled'), that it actively notifies recipients, the privacy implication of the default per-recipient threading, and the disclosure risk of group threads. These are exactly the behavioral traits an agent needs before mutating state.

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 the action and the highest-stakes warning ('NOTIFIES PEOPLE'), followed by usage rules and then parameter notes. Every sentence adds information the schema does not already carry; nothing is padding.

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?

An output schema exists, so return values need no explanation here. Combined with the parameter notes and the approval/privacy guidance, an agent has everything required to invoke this correctly and safely.

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 0%, yet every parameter is explained: recipient_ids accepts a comma-separated list or JSON array, group_conversation controls thread sharing with a stated default, and course_id's scoping effect and fallback to CANVAS_DEFAULT_COURSE_ID are spelled out. This fully compensates for the absent schema descriptions.

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 ('Send a Canvas inbox message to one or more students'), cleanly distinguishing it from sibling announcement and discussion tools. An agent can tell immediately this is direct messaging, not a public post.

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?

Gives explicit when/when-not guidance for group_conversation ('only pass group_conversation=True when students are meant to see each other') and a required approval workflow before every send. It stops short of naming a sibling alternative (e.g. post_announcement) for the broadcast case, but the operating conditions are clear.

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