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

Annotations already cover the read-only, non-destructive, idempotent nature of the tool. The description adds useful behavioral context by explaining that CIKs are accepted with or without leading zeros and that the result is a normalized 'unified company profile'. This goes beyond the schema and annotations without contradicting them.

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 a single, front-loaded sentence followed by a compact illustrative example. Every element earns its place, and there is no redundant filler. It is highly scannable for an agent.

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 one-parameter lookup with safety annotations and no output schema, the description is complete. It explains what input is accepted, how the input may be formatted, and what kind of result is returned. No additional details are necessary for a correct tool selection or 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 100%, so the baseline is 3. The description and schema both give the '320193' / '0000320193' examples, adding only the Apple mapping. The parameter's meaning is clear, but the description does not substantially enrich the schema's own documentation.

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 ('Resolve') and resource ('SEC EDGAR Central Index Key') with a precise output ('unified company profile'). The example '320193 = 0000320193 = Apple' makes the tool's purpose unmistakable. It also differentiates from sibling company identifier tools by focusing specifically on SEC CIK rather than ticker, domain, or EIN.

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 clearly implies the use case: when you have an SEC CIK and want a company profile. It notes that CIK formatting is flexible, which removes a common usage question. It does not explicitly mention alternatives like company_ticker or company_domain, so it lacks the 'when-not-to-use' guidance needed for a 5.

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