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

Beyond the readOnly and idempotent annotations, the description reveals meaningful behavior: internal cascading lookups, graceful degradation when GLEIF/OpenFIGI are unavailable, and how non-equity instruments without tickers still resolve. This adds substantial context the annotations do not provide.

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 front-loaded with purpose and usage, and every major clause carries useful information. However, it is a dense single paragraph with heavy nesting, so it is not as scannable as it could be; this prevents a 5.

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?

With no output schema, the description compensates by documenting returned identifiers for each type, accepted input forms, ownership data, citation URLs, and fallback behavior. An agent has enough to select inputs and interpret results 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 though the schema already describes both parameters, the tool description enriches them significantly: it explains accepted inputs for company (ticker, CIK, ISIN, name) and drug (brand or generic), and warns to pass only the entity name, not the full noun phrase. This goes well beyond the schema's baseline.

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 opens with concrete user queries and states the tool's core job: resolve a user-spoken NAME to canonical/official identifiers other tools require. It names supported types and specific identifier outputs, making it clearly distinct from sibling tools like entity_profile or compare_entities.

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?

It gives explicit guidance: 'Use FIRST whenever you have a name but need an ID,' and provides illustrative query patterns. It does not explicitly name alternative tools or state when not to use it, so it stops short of a 5.

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