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

With no annotations, the description carries full behavioral burden. It comprehensively discloses behavior: returns matched rung and currency, resolves retired identifiers by default with replacement details, and clarifies issuer keys return multiple securities. Coverage statistics add expected hit-rate context. This is exemplary transparency.

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 long but every sentence adds value: purpose, constraints, retired behavior, issuer behavior, use cases, and coverage stats. It is front-loaded with the core function and uses uppercase for key constraints, making it scannable despite length.

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?

Given 10 parameters, no annotations, and no output schema, the description covers inputs, behavior, coverage, and use cases well. It lacks explicit error handling details but provides enough context for an agent to select and invoke the tool correctly. The coverage stats are a strong contextual addition.

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 0%, so the description must compensate. It explains most parameters through synonyms (e.g., 'regulator filer number' for cik, 'estimate-vendor ticker' for ibtic) and describes the include_retired behavior. However, the mapping is not always explicit, and a few parameters like entity_id/private_company_id are only mentioned in passing, but overall it adds significant meaning.

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 identifies a reverse identifier lookup with a specific verb and resource, listing supported identifier types and what is returned. It distinguishes from siblings by stating 'Exactly one identifier per call' and referencing batch capabilities implicitly, and the coverage data further differentiates it.

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 gives explicit use cases: converting CUSIP-keyed files, finding tickers from regulator filings, and auditing stale identifiers. It also implies constraints like single identifier per call and discloses retired resolution behavior, but does not explicitly name alternative tools like batch or crosswalk, leaving a small gap.

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