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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description does not need to restate those. It adds context about the types of funds and data fields, but it does not disclose additional behavioral traits such as pagination, data freshness, or response limits beyond the schema. Since the annotations cover the safety profile, the description's added value is limited but acceptable.

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 three short sentences with the main purpose front-loaded. The 'Input' sentence is somewhat redundant with the schema but adds minimal overhead. Overall it is efficient and well-structured, without fluff.

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?

Given that the tool has an output schema and annotations for read-only and open-world behavior, the description adequately covers the core use case and data fields. It is complete for a simple directory lookup, though it could have mentioned how `async` interacts with the tool, but that is already explained in the 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?

The description mentions 'optional country and limit' but adds little beyond the input schema. The schema already documents `async` fully and provides a description for `country`; `limit` has min/max constraints. With schema coverage at 67%, the description does not compensate for the missing `limit` semantics or clarify any parameter beyond what the schema provides.

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 clearly states the tool 'Return investors from the FTG directory' and enumerates the specific data fields (type, firm, website, ticket-size range, sectors, stages), making the function concrete and distinct from generic investor tools. The reference to 'FTG directory' and the listing of VC, PE, and impact funds provides a specific resource and scope.

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: 'an agent builds a fundraising shortlist.' This gives a clear contextual trigger. However, it does not mention when not to use it or name alternative sibling tools like investor_list or investor_shortlist, so it lacks explicit exclusions.

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