schwab_get_instrument_by_cusip

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

No annotations exist, so the description must fully explain behavior. It only mentions that leading zeros are preserved, but does not disclose whether the tool is read-only, error handling for invalid CUSIPs, or any side effects. The behavioral profile is largely unspecified.

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 very concise with two sentences, but effectively front-loads the purpose and includes a parameter block. While minimal, every sentence serves a purpose, earning a high score for conciseness.

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?

Despite an output schema existing, the description lacks completeness for a tool in a large sibling set. It omits error scenarios, return format hints, and comparison to similar lookup tools. The agent is left without sufficient context to use it robustly.

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 0% description coverage, and the description compensates fully by explaining the CUSIP format with an example ('037833100') and noting that leading zeros are preserved. This adds crucial meaning beyond the schema's bare type definition.

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 retrieves instrument details by CUSIP identifier, specifying the verb 'get', resource 'instrument details', and unique key 'CUSIP'. This distinguishes it from sibling tools like schwab_quote or schwab_search_instruments.

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 no guidance on when to use this tool versus alternatives (e.g., symbol-based lookups). It does not mention prerequisites, fallback, or exclusions, leaving the agent uninformed about appropriate context.

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