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

Beyond the readOnlyHint/openWorldHint/idempotentHint annotations, the description adds genuinely valuable behavioral detail: LEI/FIGI enrichment degrades gracefully if external sources are unavailable, each call cascades through multiple lookup endpoints internally, and non-equity instruments and non-US issuers are covered. These are non-obvious behaviors an agent needs to know before invoking the tool.

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 the tool is genuinely complex with two entity types and multiple data sources. It front-loads the core purpose and usage cue, then organizes detail under 'SUPPORTED TYPES.' The final sentence about replacing manual lookups is slightly promotional but still informative about the tool's internal cascading behavior.

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 there is no output schema, the description does well to enumerate returned identifiers for both company and drug lookups, and it covers degradation behavior when enrichment sources fail. It is slightly less explicit about how completely unresolved names are represented or whether multiple candidates can be returned, but the core invocation context is complete.

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%, but the description still adds parameter meaning beyond the schema: it explicitly mentions ISIN as an accepted company input, explains that ISINs resolve via GLEIF ISIN-to-LEI mapping, and clarifies that non-equity instruments without tickers still resolve. The schema's value description is already strong, so the description's additions are incremental but useful.

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 that the tool resolves user-spoken entity names into canonical/official identifiers that other tools require as input. It enumerates concrete example queries, supported entity types (company, drug), and specific identifier outputs, making the tool's purpose unambiguous. The phrase 'other tools require as input' differentiates it from entity-consuming siblings.

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 a direct routing rule: 'Use FIRST whenever you have a name but need an ID.' This is clear when-to-use guidance. It does not explicitly name alternatives or state when not to use the tool, but the 'other tools require as input' framing implies that if an ID is already available, this tool is not the target.

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