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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds meaningful behavioral context beyond annotations by specifying the exact return contents (per-requirement statuses, explanations, limitations, sources) and the explicit 'no published comparison yet' empty-state behavior. This is valuable, non-redundant disclosure.

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?

Two sentences with no filler. The purpose and key output details are front-loaded, and every clause adds information. The description is concise and well-structured.

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, idempotent comparison tool with 3 parameters and no output schema, the description covers the essential return values and the empty case. It does not mention pagination or error handling beyond the no-comparison case, but these are minor for this tool type. The description is sufficient for an agent to know what to expect.

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 input schema provides 100% coverage with descriptions for all three parameters (vendor_a, vendor_b, category). The tool description does not add additional parameter-level detail beyond what the schema already provides, so the baseline score of 3 is appropriate. It does not introduce syntax or format details that would raise the score.

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 performs a head-to-head comparison of two vendors over published, gate-passed findings, and enumerates the specific outputs (per-requirement statuses, mechanism explanations, limitations, sources, canonical URLs). This distinguishes it from siblings like list_vendors and search, which are for listing or general queries.

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 implies the use case (comparing two vendors) but does not explicitly state when to use this tool versus alternatives such as search or fetch. There is no 'when not to use' guidance or reference to sibling tools. It is clear enough but lacks explicit routing.

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