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

The description goes well beyond the readOnly/idempotent annotations by disclosing fallback behavior (LEI/FIGI enrichment degrades gracefully, EDGAR identifiers still return), source labeling, explicit treatment of unresolvable identifiers under `unresolved`, and internal cascading through multiple endpoints. It also explains how ISINs are mapped to legal entities. This gives an agent an accurate mental model of what happens under success and partial-failure conditions.

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 section carries decision-relevant information: examples, supported types, input constraints, fallback behavior, and endpoint cascading. It is front-loaded with the core purpose and the "Use FIRST" guidance before diving into detail. The heavy use of nested parentheticals makes it dense to parse, but not bloated relative to the tool's complexity.

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 carries the full burden of explaining return fields, and it does: CIK, ticker, company_name, LEI, FIGI, RxCUI, ingredient, brand, citation, and `unresolved`. It also covers edge cases like non-equity instruments, non-US issuers, ISIN input, and brand/generic drug names. For a two-parameter lookup tool with rich behavior, nothing critical is missing.

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 schema coverage is 100%, the description adds critical meaning beyond the parameter schema. For `value`, it explicitly warns to pass the entity name only, never the question's full noun phrase, and gives a concrete example with "NEW YORK ST DORM AUTH" versus the invalid "NEW YORK ST DORM AUTH revenue bonds." It also explains what each `type` accepts and returns, which materially improves invocation correctness.

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 names the exact job — resolving a user-spoken name to canonical identifiers that other tools require — and is packed with concrete example queries. The instruction "Use FIRST whenever you have a name but need an ID" clearly separates it from sibling tools that consume already-resolved IDs. It is specific, actionable, and not merely a restatement of the title.

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 explicitly states when to use the tool: "Use FIRST whenever you have a name but need an ID." It also explains that it replaces 2-3 manual lookups, which frames it as a preliminary step before other tools. It does not name sibling tools or give explicit when-not-to-use guidance, but the core routing instruction is strong and unambiguous.

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