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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds genuinely non-obvious behavior: the result set depends on the caller's role, widening for Lecturers to sent and scheduled messages. However, it says nothing about ordering, pagination, or volume for a potentially long message list.

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?

One sentence with zero filler, front-loading the core action and resource before the role-based qualifier. Nothing could be removed without losing information.

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 single-parameter, read-only, closed-world listing tool with full annotation coverage and no output schema, the definition covers the essentials plus the role-dependent scope. The only meaningful gap is the absence of any indication of result size, ordering, or pagination behavior for a message collection.

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?

There is a single parameter with 100% schema description coverage, and the schema already explains that courseId comes from list_courses. The description adds no further meaning about the parameter, 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 ('Reads') and resource ('Course Messages') and narrows scope to messages the person received, with a role-based exception for Lecturers. Sibling tools all target different resources (pages, files, sessions, tasks, members), so the resource name alone distinguishes it, though no sibling is named explicitly.

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?

Usage is implied rather than stated: an agent can infer this is the tool for reading course messages, but there is no explicit when-to-use, when-not-to-use, or guidance on alternatives for message retrieval. The Lecturer clause clarifies the result set but not the invocation decision.

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