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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds non-obvious operational context: an API key is required and a free StartupHub.ai account is needed, plus the result shape includes a 'reason' per match. It stops short of describing pagination, limits, or failure modes.

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 short sentences, front-loaded with the core behavior and then the two input directions. Every clause carries information; there is no restatement of the title beyond the opening label.

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 no output schema, the description usefully notes that each match carries a reason, and it covers auth requirements and the bidirectional input rule for a tool whose required enum is undocumented in the schema. It is essentially complete for invocation, missing only volume/limit expectations.

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 67% and the schema documents id/slug as 'slug or id', but the required 'type' parameter carries no description in the schema. The description supplies exactly that missing semantics: type selects the direction of the match, so the agent knows 'type' is not merely a filter but the determinant of the result set.

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 ('find') and spells out both directions of the operation: startup id/slug in, investors out, and vice versa. This clearly separates it from plain lookup siblings like get_startup or get_investor_by_domain, though it never explicitly names an alternative.

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?

Usage is implied through the input-direction rule ('Given a startup slug or id...' / 'Given an investor slug or id...'), which tells the agent how to drive the tool. There is no guidance on when to prefer this over search_investors or match_companies_by_domain, and no exclusions or prerequisites beyond the account note.

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