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

Annotations already declare a safe read operation (readOnlyHint=true, destructiveHint=false, openWorldHint=false). The description adds genuinely useful context beyond them: the Professional-plan requirement and the fact that calling it while signed out initiates a sign-in flow, which materially affects agent 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 short sentences, front-loaded with the core purpose and return value, followed by access and auth constraints. Every sentence carries information; nothing is wasted.

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 one parameter, full schema coverage, and no output schema, the description compensates by summarizing what comes back (full details plus a comparison matrix) and covering access/auth prerequisites. Nothing an agent needs to invoke it correctly is missing.

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 single 'slugs' parameter is fully documented with minItems/maxItems. The description's '2–5 providers' merely restates the schema bounds, adding no new syntax or format meaning, so the baseline 3 applies.

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 (compare) and resource (providers), plus the exact cardinality (2–5 side by side) and the output shape (full details plus a per-criterion comparison matrix). This implicitly and cleanly distinguishes it from the single-provider get_provider_detail sibling.

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 'compare 2–5 providers side by side' framing makes the use case clear, and the plan gating (Professional and above) tells the agent when the tool is callable. It does not explicitly name an alternative such as get_provider_detail for single-provider needs, so it stops short of the top score.

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