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

The description repeats the annotation statements (Read-only, no side effects, idempotent), which is redundant but consistent, so no contradiction. It adds valuable context beyond annotations: 'US only', '24-hour cache', and 'Verified source: FINRA BrokerCheck'. This additional information about data freshness and provenance goes beyond what annotations provide, although it doesn't detail response format or error behavior. Given annotations already cover the safety profile, the description adds meaningful context, earning a 4.

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?

The description is somewhat long but densely packed with necessary information. It front-loads the purpose and then covers parameters, usage guidance, alternative, source, cache, and a feedback fallback. While the repeated safety statements ('Read-only. No side effects. Idempotent.') are redundant given annotations, they don't waste much. The structure is logical and each segment serves a purpose, so it ranks above average but not perfect due to slight 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?

Given the tool has an output schema (though not shown) and annotations cover the safety profile, the description provides everything needed for correct invocation: the primary input, its format, limitations (US only, no name lookup), alternatives, source verification, cache behavior, and a fallback mechanism via report_feedback. This is comprehensive for a simple one-parameter tool with rich structured metadata.

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?

Although the schema description provides the parameter name and a basic description, the tool description offers substantial added meaning: it specifies that the CRD number must be 'a string of digits', provides an example ('1234567'), states it is required, and clarifies that only CRD lookup is supported (not name lookup). This is significant semantic enrichment beyond the schema, which only states the format requirement. Since schema coverage is 100% but description goes further, it earns a 5.

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?

The description clearly states the action ('Fetch'), the resource ('FINRA BrokerCheck registration'), and the specific scope (US brokers or investment advisers by CRD number). It distinguishes from sibling tools by explicitly stating it is not for healthcare providers and points to an alternative. The purpose is unambiguous and specific.

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?

The description provides explicit when-to-use guidance: 'Use this when you have the CRD number' and explicitly names the alternative for healthcare providers ('Use compliance_search_npi_by_name instead'). It also states that name lookup is not supported, preventing misuse. This clearly guides the agent on when to select this tool over siblings.

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