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

Beyond the readOnly/idempotent annotations, the description discloses rich behavior: internal cascading through multiple endpoints, graceful degradation when GLEIF/OpenFIGI is unavailable, ambiguity handling (asserts nothing and returns figi_candidates), explicit unresolved fields, and ISIN-to-LEI mapping. This is exactly the kind of contextual behavior annotations can't capture.

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 dense and almost entirely useful, but it's organized as sprawling parentheticals and a long run-on sentence covering FIGI, ambiguity, unresolved fields, and ISIN mapping. Breaking it into bullets or separate sentences would preserve the detail while improving scannability.

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 tool with no output schema, the description covers the key response behaviors (figi_candidates, unresolved, source-labelled identifiers) and all valid input forms. It doesn't spell out the exact top-level output shape, but the named fields and fallback semantics are enough 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?

Even with 100% schema coverage, the description adds critical nuance: for bonds, the value must be the issuer exactly as printed because FIGI matches instrument names; a ticker implies an exact-ticker map; an ISIN resolves to the issuing legal entity. This guidance prevents realistic failure modes beyond the schema's brief explanation.

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?

States a specific verb and resource: resolving a user-spoken NAME to canonical identifiers (CIK, ticker, LEI, FIGI, RxCUI). It clearly differentiates from siblings by positioning itself as the prerequisite lookup step ('Use FIRST whenever you have a name but need an ID') and enumerating exactly what identifiers it produces.

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?

Provides an explicit trigger condition: use it whenever you have a name but need an ID. It also distinguishes from sibling research/comparison tools by focusing solely on identifier lookup. However, it never explicitly names alternatives to use when the condition doesn't apply, so it stops short of full exclusions.

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