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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds non-obvious behaviors: typo forgiveness, best-match-first ordering, inclusion of former ticker-directory companies (listing_status former), and the specific output fields. This goes beyond the structured data and helps the agent predict results.

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?

Three sentences with no filler: the first states the core function and output fields, the second clarifies inclusion of delisted companies, and the third gives the usage routing. Information is front-loaded and every sentence adds value.

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 2-parameter lookup tool with no output schema, the description lists every returned field (ticker, CIK, name, exchange, sector/industry, latest annual period end), explains inclusion policy, and states the ordering behavior. This is sufficient for an agent to call it correctly and understand the result.

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% with parameter descriptions containing examples (e.g., 'apple, berkshire, or msft') and the limit constraints. The description does not add further parameter-level meaning beyond the schema, so it meets the high-coverage baseline of 3.

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-resource pair: 'Find US public companies by name or ticker', details the returned fields, and explicitly positions the tool as the ticker resolver for other tools ('Use it to turn a company name into the ticker the other tools take'). This clearly distinguishes it from the sibling get_* and screen_companies 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 signal: use it to convert a company name into a ticker for downstream tools. It does not name alternative tools or provide when-not-to-use guidance, but for a focused lookup tool this is a clear and sufficient context.

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