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

With no annotations provided, the description must convey behavioral traits. It discloses the read-only nature of searching and lists example output fields, which is useful. However, it does not describe potential error cases, whether multiple matches are returned, or the exact response structure. It adds some value but lacks comprehensive behavioral disclosure.

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 concise, consisting of two sentences that front-load the purpose and provide helpful examples. No unnecessary details or filler. Every sentence contributes to understanding the tool's function.

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?

The tool is simple (one parameter, no output schema), and the description covers its core purpose and example outputs. It provides enough context for an agent to decide when to use it. However, it does not describe the return format or behavior when no match is found, which would improve completeness given the absence of an output schema.

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 input schema already provides a description for the 'cusip' parameter ('The CUSIP number to search for'), so schema coverage is 100%. The description adds minimal extra meaning by repeating 'by CUSIP number' but does not explain CUSIP format or constraints. Baseline of 3 is appropriate since the schema carries the parameter semantics.

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 tool's function: 'search and retrieve financial securities information by CUSIP number.' It specifies the resource (CUSIP API) and the output fields (company name, stock symbol, market capitalization). This distinguishes it from sibling search tools like searchISIN or searchCIK by the identifier type.

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 implicitly indicates when to use the tool: when you have a CUSIP number. It does not explicitly compare to alternatives or state exclusions, but the context is clear. The phrasing 'by CUSIP number' establishes the appropriate use case without mentioning when not to use it.

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