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. The description adds ordering ('newest first'), which is genuinely useful and not in the schema, but says nothing about whether results are truncated by limit, pagination, or what a returned record contains.

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?

A single compact sentence with the filter front-loaded and the ordering appended. No wasted words, though the terseness leaves gaps that other dimensions penalize.

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 simple two-parameter read tool with annotations and no output schema, the definition is minimally adequate. It still leaves open whether it returns user objects or a count, and whether limit truncates silently.

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 0%, so the description must carry parameter meaning. It clarifies that 'days' means the signup window and restates the default of 7 (already in the schema), but says nothing about 'limit' (default 20, max 50) – whether it caps rows returned and what happens when more users exist.

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 concrete resource and filter: users who joined in the last N days, with explicit ordering (newest first). An agent can distinguish this from list_users or find_users_at_risk, though it does not name those siblings 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?

There is no guidance on when to choose this over get_active_users, get_growth_report, list_users, or detect_abnormal_signups. Usage is only implied by the phrase 'joined in the last N days'.

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