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

Annotations only cover safety/idempotency hints; the description adds real operational context the annotations cannot: 2-credit cost with automatic refund when nothing is found, the PeopleSearch.im opt-out guarantee, and the Verified/Likely confidence label plus LinkedIn match in the result. This is exactly the extra behavioral detail the annotations leave out.

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?

Four sentences, front-loaded with purpose then parameters then cost/privacy then routing. Every sentence carries information the agent needs (inputs, cost, result shape, alternative tool); nothing is padding.

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?

With no output schema, the description compensates by describing the return (email + confidence label + optional LinkedIn URL). Cost, refund behavior, privacy exclusion, and sibling routing are all covered for a 3-param open-world lookup tool.

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% and the schema already documents all three fields, including the 'domain (best)' hint, so the description largely restates it. It adds marginal value by reiterating that a domain matches best, but no new syntax or format guidance. Baseline 3 applies when the schema carries the load.

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+resource combination ('find and verify the professional (work) email of a person') and explicitly scopes it to people the caller can already name. It also names the sibling tools (people_search, find_people, fetch_email) it is not, so an agent can route without opening a schema.

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?

Gives a clear when-to-use condition (you can name the person: first name, last name, company) and an explicit when-not path with alternatives ('To find people you cannot name yet, use people_search or find_people, then fetch_email'). Nothing is left to inference.

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