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

Annotations already cover read-only, idempotent, non-destructive and open-world behavior. The description adds a genuinely non-structured trait: that reading costs no credits (contrasted with the paid reveal_contacts path), plus the fact that emails may be absent. No pagination or result-limit behavior is disclosed.

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 resource and returned fields, then the input provenance, then cost and the upsell path. No filler or repetition of schema content.

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 two-parameter read tool with no output schema, the description covers what is returned, where the input comes from, and the cost model. It is close to complete; only result-size/limit behavior is unaddressed.

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 both parameters are already documented in the schema, including the id/slug format example. The description adds little parameter-specific syntax beyond implying the email filter via 'email where we have it'. Baseline 3 applies when the schema does the heavy lifting.

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 ('Get the people Fundz already holds for one company') and enumerates the returned fields. An agent can distinguish it from search_funding_rounds (which supplies the id) and from reveal_contacts (which enriches), so sibling differentiation is present.

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?

Explains where the 'company' argument comes from ('id or slug returned by search_funding_rounds and the other feeds') and points to reveal_contacts for the follow-up case of a contact with no email. It stops short of explicitly stating when not to call this tool, but the routing context is clear.

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