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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description reinforces these with 'Read-only. No side effects. Idempotent.' and adds further behavioral context such as 'US only', '24-hour cache', and 'Verified source: FINRA BrokerCheck.' There is no contradiction with annotations.

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 fairly long but well-structured and front-loaded with the main purpose. It includes necessary details but could be slightly more concise. However, the organization is clear and every sentence adds value, so it earns a 4.

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, the description appropriately summarizes return values ('Returns registration status, qualifications, disclosure history, and employment history'). It covers all necessary aspects: purpose, limitations (no name lookup), source, caching, and fallback. For a simple one-parameter tool, this is complete.

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?

The schema has 100% coverage for the single parameter crd_number, so baseline is 3. The description adds value by explaining what a CRD number is ('Central Registration Depository number as a string of digits e.g. 1234567'), reinforcing that it's required, and clarifying that name lookup is not supported. This extra context justifies a higher score.

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 'Fetch FINRA BrokerCheck registration for a US broker or investment adviser by CRD number.' It uses a specific verb (fetch) and resource (FINRA BrokerCheck registration), and distinguishes itself from sibling tools like compliance_search_npi_by_name by specifying it's for financial advisers, not healthcare providers.

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 usage guidance: 'Use this when you have the CRD number.' It also states when not to use it ('name lookup is not supported') and directs users to an alternative tool for healthcare providers. Additionally, it includes a fallback instruction to report feedback if the tool doesn't serve the need.

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