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

Beyond the readOnlyHint annotation, the description discloses key behavioral traits: scope is limited to previously run measurements, results include which engines named the competitor, frequency, last-seen timing, and co-named competitors, and it also reports domain citations. The coverage caveat is especially valuable for correct interpretation of absence.

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 efficiently written and front-loads the core direction-first framing ('Reverse lookup over every measurement we have already run'). The first sentence is long and enumerative, but it earns its length by compensating for the missing output schema.

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 enumerates the result contents clearly: buyer questions, engines, frequency, last seen, co-named parties, and citation sources. Combined with complete parameter schema documentation and the important coverage caveat, an agent has enough context to invoke and interpret the tool 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 coverage is 100%, so all four parameters are already documented in the schema. The description adds interpretive context about coverage and result meaning but does not provide substantial new parameter-level semantics beyond what the schema already gives.

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 and resource: 'Reverse lookup' over measured buyer questions, returning where a competitor was named or cited. It clearly distinguishes this from forward source lookups by framing it as the inverse direction, and the coverage caveat further clarifies exactly what the tool does.

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 clear context for when to use this tool: when you have a competitor's brand name or domain and need the buyer questions that named it. It also provides interpretive guidance about thin results meaning unmeasured questions, not competitor absence, though it does not explicitly name sibling alternatives or when not to use it.

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