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

Annotations declare readOnlyHint and idempotentHint as true, so the tool is safe and idempotent. The description adds context about returning 'full provenanced records' and a 'notFound list' for unknown slugs, detailing behavioral traits beyond annotations.

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 two sentences, front-loading the main action and purpose. Every element is necessary: verb, resource, examples, parameter guidance, and return value. No wasted words.

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?

Despite no output schema, the description explains the return (full provenanced records and notFound list). It covers usage scenario, parameter guidance, and expected behavior, making it complete for the tool's complexity.

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?

With schema description coverage at 50% (only 'section' has a description), the description compensates by explaining 'slugs' are vendor slugs with examples, and specifying the default value for 'section'. This adds significant meaning beyond the bare schema.

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 compares specific vendors by slug within a theme, with examples for 'ai-receptionists' and 'vpn-services'. It distinguishes itself from the sibling 'compare_products' by focusing on vendors, and from other tools like 'list_sections' by its comparison functionality.

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 advises setting 'section' to a theme slug from 'list_sections' and to call 'list_sections' or 'list_coverage' for full slug lists. It does not explicitly exclude scenarios but provides clear context for when to use this tool, such as comparing multiple vendors in a specific theme.

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