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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds real context beyond that: result shape (up to 20 summaries per page with email counts per company), that no API key is needed, and that no contact data is revealed. It stops short of describing rate limits or sort/ordering behavior.

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 tight sentences, front-loaded with the primary lookup use, then the list-building use, then the sibling routing. Every sentence carries distinct information; nothing is padding.

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 9 optional parameters, no output schema, and read-only annotations already present, the description fills the remaining gaps: it explains the paginated return payload and the email-count field, and it clarifies that query short-circuits the filters. An agent has everything needed to invoke it correctly.

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 description coverage is 100% and the enum labels are already documented, so the schema does the heavy lifting. The description adds only a light restatement of the query-vs-filter exclusivity that the schema itself already states, so the baseline 3 is correct.

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 (find/build a list) over a specific resource (companies), and enumerates the exact filter dimensions the tool searches on. It also names what it is not — lookup_company and get_technologies — so the agent can distinguish it from siblings without opening any schema.

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 (find one company by name/domain vs. build a list by sector, model, B2B/B2C, tech, country) and pairs each with the correct alternative (lookup_company for a full single record, get_technologies to page all companies using a tool). Routing is unambiguous.

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