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

readOnlyHint=true already establishes the safety profile, so the description's contribution is the peer-selection rule (country + GICS sub-industry), which is genuinely useful context. It does not disclose whether the queried symbol is included in the result, ordering, or behavior for unknown symbols. The 'grouping' parameter also implies selectable criteria that the fixed description sentence does not reconcile.

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?

Two short sentences, zero filler, with the resource and its scoping rule front-loaded and the REST provenance last. Nothing needs trimming.

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 two-parameter read tool with no output schema, annotations covering safety, and full schema coverage, the description is adequate. It could add a word on the returned peer list format or symbol treatment, but nothing essential for correct invocation is 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 100%, so the schema already documents both 'symbol' and 'grouping' at the baseline level. The description adds the underlying selection rule, but it also creates a mild tension: it fixes peers to sub-industry while 'grouping' accepts 'sector' and 'industry' without explanation.

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 resource ('Peer companies for a symbol') plus the exact scoping rule ('same country and GICS sub-industry') and the upstream REST endpoint, which removes the main ambiguity of what 'peers' means. It is trivially distinguishable from siblings like finnhub_quote, finnhub_company_profile, or finnhub_recommendation_trends.

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?

Usage is only implied: the scoping sentence tells the agent what the tool returns but never states when to prefer it over finnhub_company_profile or finnhub_recommendation_trends, nor any exclusions (e.g., unsupported exchanges or symbols). No explicit alternative or precondition is given.

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