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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint true and destructiveHint false. The description adds useful behavioral detail beyond that: list endpoints are paginated, there is a 30-record-per-page cap, and the response includes a pagination object with current_page, last_page, and total to guide further fetching. No contradiction with annotations.

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 body is compact and front-loaded: purpose in the first paragraph, pagination usage in the second. The only redundancy is the opening 'List Messages' line, which repeats the tool title, so it isn't a perfect 5.

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?

Given 10 optional parameters, rich schema, output schema, and annotations, the description covers the core call and pagination behavior. However, it leaves the relationship to listCustomerMessages unspecified and uses the vague term 'recent' without defining the default time range, so an agent could still be uncertain about tool selection and scope.

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?

Input schema coverage is 100%, with each parameter described in the schema itself (e.g., date_from/date_to format, date_key enum, limit max 30). The description mentions page/limit and calendar bounds but does not add meaning beyond the schema, so it sits at the baseline of 3.

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 description clearly states a specific action and resource: retrieve recent project outreach messages for reporting or auditing, and mentions optional calendar bounds on a datetime column. It distinguishes the tool from unrelated list endpoints (e.g., listCharges, listCustomers) but does not explicitly contrast with the sibling listCustomerMessages, so it falls short of a 5.

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?

It provides clear usage context for reporting/auditing and explains pagination via page/limit and inspecting the pagination object. However, it gives no when-to-use vs alternatives, particularly failing to say when to choose listMessages over the sibling listCustomerMessages, leaving the selection criterion implied.

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