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

Annotations declare idempotentHint=true, readOnlyHint=false, destructiveHint=false. The description adds substantial context beyond these: it 'triggers no email to the address given,' 'updates the existing record rather than creating a duplicate' (reinforcing idempotency), 'No authentication. Rate-limited per IP address,' and notes it returns a plain-text confirmation. No contradiction with annotations; it enriches them.

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 description is on the longer side (5 sentences) but every sentence earns its place: purpose, uniqueness, usage constraint, idempotency, and auth/rate-limit. It is front-loaded with the core purpose first, and the structure flows logically from what → why → when → behavioral caveats. Slightly verbose but appropriately dense.

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 4-parameter write operation with no output schema, the description covers everything an agent needs: purpose, what it writes, what it returns (plain-text confirmation), idempotency, auth requirements, rate limits, and the consent gate. The annotations carry the safety profile and the description fills the return-value gap since there's no output schema. Nothing essential is missing.

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 coverage is 100%, so the baseline is 3. The schema already documents all four parameters clearly (email is required, name/company/note optional, with descriptions like 'given by them for this purpose'). The description adds marginal value by grouping them as 'optional name, company and note' and confirming email as the core input, but does not go beyond what the schema provides.

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 states a specific verb ('Records'), a specific resource (email address → lead record on zRev's side), and the purpose ('so that zRev's founder can reach out'). It also explicitly differentiates from siblings by declaring 'This is the only tool here that writes data,' so an agent can immediately distinguish it from book_call, estimate_roi, etc.

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 description gives explicit when-to-use guidance: 'Use only when the human you are assisting has explicitly asked to be contacted by zRev' and clear exclusions: 'never call it speculatively or with an address the user has not given you for this purpose.' This is the strongest form of usage guidance — a positive condition plus a negative prohibition.

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