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

Annotations already cover safety (readOnly, idempotent, non-destructive), and the description adds real behavioral context beyond them: result ordering (most companies first), a hard cap of 50, the shape of each row, and the volume cost of the no-query path. That cost/benefit disclosure is exactly what annotations can't express.

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?

Front-loaded with the purpose and the return shapes, with no filler sentences. The trailing "Args:" block duplicates the schema's optional query and is the one piece that doesn't earn its space.

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?

An output schema exists, yet the description still tells the agent enough about both return modes to choose correctly and to consume the result. Nothing needed to invoke this tool correctly 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?

The single parameter has 0% schema coverage, so the description must carry it, and it does: query is a word matched against industry titles, with concrete examples ("software", "bank", "oil", "pharmaceutical"), marked optional, and its absence is defined. It stops short of stating the matching rule (substring/prefix/case), leaving a small ambiguity.

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?

States a specific verb and resource ("List the SEC's SIC industry codes") and immediately names the downstream sibling it feeds, list_companies_by_sic. It also explicitly distinguishes SIC from GICS and NAICS, which prevents a whole class of misclassification.

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?

Gives explicit when-to-use branches: with a query you get matching codes ranked by company count; with no query you get all ~440 codes, and it advises "prefer a query." It also routes the agent onward (list_companies_by_sic for a code, get_company for a single company's own code).

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