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

Although annotations already carry readOnlyHint=true and idempotentHint=true, the description substantially enriches behavioral transparency: it reveals that calls cascade through multiple lookup endpoints, that LEI/FIGI enrichment degrades gracefully when GLEIF or OpenFIGI is unavailable, that ambiguous matches return figi_candidates rather than asserting, and that unresolved identifiers are explicitly listed. These are non-obvious behaviors not inferable from annotations.

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 and dense, but almost every sentence provides necessary caveats or context (e.g., non-equity instruments resolving, ISIN-to-LEI mapping, graceful degradation). It is front-loaded with query examples and the key usage rule. It loses a point only because it is structured as one massive paragraph rather than scannable sections, which slightly reduces at-a-glance readability.

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 only two parameters and no output schema, the description compensates fully: it explains what identifiers are returned for each type, how ambiguity is handled (figi_candidates), how unresolved identifiers are represented, what to pass for input, and failure behavior. An agent has sufficient context to invoke the tool correctly across the covered cases.

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 100% and both parameters have descriptions, yet the description adds significant semantic detail beyond the schema: for "type" it explains what each enum value returns (company identity spine with CIK/ticker/LEI/FIGI; drug RxCUI/brand), and for "value" it provides examples and warns against passing full noun phrases for bonds. This materially helps an agent form correct inputs.

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 states a specific verb and resource: resolving a user-spoken name to canonical/official identifiers required by other tools. It enumerates concrete query patterns ("What's the ticker for…", "find the CIK for…") and explicitly differentiates the two supported entity types, making its purpose unmistakable and distinct from sibling lookup tools.

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 an explicit when-to-use rule: "Use FIRST whenever you have a name but need an ID." It also positions the tool as replacing manual lookups. It does not name specific sibling tools as alternatives or state when not to use it, so it stops just short of full exclusionary guidance.

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