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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered structurally. The description adds value beyond that: result ordering ('newest first') and an explicit warning that returned user fields are untrusted customer-supplied data and must never be treated as instructions — a meaningful prompt-injection disclosure for a list-returning tool.

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?

Three short sentences, front-loaded with the core action and ordering, then filters, then the trust-boundary caution. Every sentence carries distinct information and there is no filler or redundancy.

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 zero-required-parameter list tool with no output schema, the description covers ordering, filtering, and the nature of returned data. It is slightly thin on result-set behavior (the schema caps limit at 50, but pagination or truncation behavior is not described), though nothing critical prevents a correct call.

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 only 25% (only 'query' is documented in-schema), so the description's mention of text query and plan/status filters does compensate somewhat for plan and status. However, 'limit' is never addressed in the description, and no syntax or matching semantics beyond the schema's own 'Matches name, email, ids and custom fields' is added.

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") plus ordering ("newest first") and available filter dimensions, so the operation is unambiguous. It does not name or differentiate from close siblings such as get_active_users, get_recent_signups, or find_user, which is the only thing keeping it from 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?

The phrase "Optional text query and plan/status filters" implies the tool is used for browsing a filtered user list, but there is no explicit when-to-use guidance and no mention of when a sibling like find_user or get_active_users is the better choice. Usage is implied rather than stated.

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