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

Annotations already declare readOnlyHint, non-destructive and closed-world, so the safety profile is covered. The description adds two useful bits beyond that: the return shape ('Returns the full person profile') and an auth prerequisite ('Needs a free StartupHub.ai account'), which an agent needs before calling.

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, purpose front-loaded, and each sentence adds new information (workflow pairing, return value, auth requirement). No padding or repetition.

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 read-only, single-parameter lookup with annotations covering safety and no output schema, the description supplies purpose, sequencing, return shape, and the account prerequisite. Nothing essential for correct invocation appears to be 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 description coverage is 0% for the single email parameter, so the description must compensate. It only restates that the lookup is 'by their email address', which maps to the parameter but adds no format, normalization, or casing guidance. Minimal compensation for the coverage gap.

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 ('Reverse-lookup a person profile') keyed on a specific input ('by their email address'). This cleanly distinguishes it from the sibling get_person_by_social, whose key is a social handle, so an agent can pick correctly without opening either 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 concrete workflow ('discover_email + validate_email: discover an email, verify it, find the person record'), which clearly tells the agent when this tool fits in a sequence. It stops short of naming exclusions or alternatives like get_person_by_social or search_people, so it is strong context rather than a full when/when-not statement.

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