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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context: ranking order (exact-ticker > exact-name > prefix > substring), the error behavior (no match -> error suggesting a shorter fragment), and the constraint that only SEC registrants with a listed ticker are searchable. This goes beyond what annotations provide, though it doesn't describe pagination or rate limits.

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 well-structured and front-loaded: the core purpose is in the first sentence, followed by routing guidance, args, return format, examples, and error behavior. Every section earns its place, and the examples are compact and illustrative. No fluff or repetition of schema details.

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 search tool with a rich output schema and full schema coverage, the description is complete. It covers what the tool does, when to use it, what it returns, how results are ranked, and what happens on error. The only minor gap is lack of pagination details, but the limit parameter and return shape make this sufficient for an agent to call it correctly.

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 the schema already documents both parameters. The description adds value by giving concrete examples of valid query formats ('AAPL', 'BRK-B' or 'BRK.B', 'Berkshire', '320193') and clarifying the limit range (1-50, default 10). It also explains the return shape ({count, companies: [...]}) which helps the agent understand what the query parameter produces.

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 states a specific verb ('Search'), a specific resource ('SEC EDGAR registrants'), and the exact purpose: returning the 10-digit zero-padded CIK needed by other edgar_* tools. It also distinguishes itself from search_dart_company by explicitly excluding Korean companies. This is a clear, differentiated purpose.

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 explicitly says when to use this tool ('when you need a CIK or to disambiguate a company name before calling get_edgar_financials/filings/insider_trades'), when not to use it ('Don't use for: Korean companies'), and names the alternative (search_dart_company). It also notes that exact tickers can skip this step, which is valuable routing guidance.

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