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

Annotations already declare readOnly/idempotent/non-destructive, and the description reinforces that with 'Read-only' plus two useful operational facts not in the annotations: an unknown id returns not found, and no API key is required. It stops short of describing response shape or limits, but the output schema covers returns, so the remaining gap is minor.

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 verb and resource, then prerequisites, then parameter detail — a sensible information hierarchy. A few clauses are redundant with structured data ('Read-only' repeats readOnlyHint, 'No API key required' is somewhat extraneous), and the quoted example queries are slightly padded, but nothing is confusing.

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 an output schema, everything an agent needs is present: entity identity, returned fields, the id-resolution prerequisite, id format, and failure behavior. No behavioral or procedural ambiguity remains that would cause a wrong invocation.

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 50%: rationale is fully documented in-schema, while personId has no schema description. The description compensates well for that half, giving format examples ('vitalik-buterin', 'satoshi-nakamoto'), marking it required, and defining the not-found behavior for bad ids. It adds nothing about the rationale parameter, but that one is already self-documenting.

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 profile of one person in crypto by id') and enumerates the returned content (name, bio, teams_count, positions, projects, social/code accounts). This clearly separates it from sibling lookups like getCoinById, getTagById, and getExchangeByID, which target different entities.

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?

Provides concrete usage exemplars ('who is Vitalik Buterin', 'background on Charlie Lee') and, crucially, an explicit routing instruction: find the personId first with search or resolveId using type 'people'. It also states the exclusion outright — 'this tool needs the exact id, not a name' — which prevents the most likely misuse.

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