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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds meaningful operational context: the 10-credit cost, automatic slug/URL resolution at no extra cost, and the ability to skip lookup by providing an id from companies_entity_id. There is no contradiction with 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 two sentences with no filler. It front-loads the tool's purpose and output fields, then gives keying and cost details compactly. Every sentence carries useful information.

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 read-only lookup tool with full parameter schema coverage and an output schema, the description covers purpose, return fields, id/slug selection, and cost. It does not discuss pagination or error cases, but those are minor for this tool given the structured annotations and output schema.

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%, so the baseline is 3. The description adds value beyond the schema by signaling that slug is the simplest path, that slug resolution carries no extra credit cost, and that passing id from companies_entity_id avoids the lookup. It also reinforces the id-or-slug mutual exclusivity.

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 opens with 'Similar companies / peers' and lists the returned fields (id, name, industry, followers, url), so the resource and output are clear. It lacks an explicit verb and does not name a sibling tool to distinguish itself from, but the purpose is still readily identifiable.

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?

It gives invocation guidance by explaining the keying options ('pass slug... or pass id from companies_entity_id') and mentions the credit cost. However, it does not explicitly state when to prefer companies_similar over nearby alternatives like companies_info or companies_enrich, so tool-selection guidance is mostly implied.

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