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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's value-add is the privacy caveat: phone/WhatsApp are returned only 'when they chose to show them', warning the agent that contact fields may legitimately be absent rather than an error. It adds no further context on cost, rate limits, or what a missing/invalid username produces.

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?

Front-loaded with the core statement, then justification for the parenthetical field lists, then the call instruction last. The three parallel field enumerations are long but earn their place, since there is no output schema to convey return shape; only the mini_app kind goes unaddressed.

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, listing the returned fields per kind is exactly the right compensation, and the conditional-privacy note is essential context. The miss is that 'mini_app' is a valid kind in the required enum but has no described return shape, so an agent handling that case gets no guidance.

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 baseline would be 3, but the description adds provenance that the schema does not: both values must be copied verbatim from a prior find result, which prevents the agent from fabricating a username. Minor gap: the enum's fourth value, mini_app, is never mentioned (the schema's username description covers the slug case only).

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 — 'Full details of one result from find' — and immediately enumerates what 'full' means for each of the three primary result kinds (skills, services with prices, hours, badges; bookingsEnabled; role/type/place). This distinguishes it from the sibling 'find' (search/list) and from 'get_person' (single kind) without the agent needing to open 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?

'from find' and 'Pass the kind and username that find returned' clearly establish the prerequisite workflow: this tool is invoked on a result produced by find. It does not, however, explicitly exclude or contrast itself with the overlapping sibling 'get_person', leaving the agent to infer which to prefer for a person result.

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