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

Annotations already declare readOnlyHint=true, so safety is covered. The only added detail is the underlying endpoint (GET /users), which merely restates read-only behavior rather than adding new context. Pagination behavior, default/max page size, and organizational scoping semantics are not disclosed despite limit and offset parameters.

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 very short sentences with the resource and scope front-loaded. The endpoint note ("Missive: GET /users") is close to filler but is brief and does not dilute the core statement.

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?

There is no output schema, so the description ideally would convey the return shape (user objects, id/name fields) and pagination behavior. For a simple, fully-parameterized read tool it is minimally adequate, but an agent gets no picture of what comes back.

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 three parameters (limit, offset, organization) are already documented in the schema. The description adds nothing about parameter usage or defaults, so the baseline 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 ("List users") and clarifies the resource with "(team members)", which disambiguates it from contacts/contact books. However, it does not distinguish it from the closest sibling, missive_list_teams, leaving the users-vs-teams boundary to inference.

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?

No when-to-use guidance, no prerequisite or exclusion notes, and no mention of alternatives among the many list_* siblings. Nothing tells an agent when listing users is the right call versus listing teams or organizations.

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