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

Annotations already establish that this is a safe, idempotent, closed-world read, so the description is free to focus on output content. With no output schema, its disclosure that results include fit, quality scores, required skill, cheapest qualifying plan and limitations meaningfully tells the agent what it will get back. It adds no auth, rate-limit or cost-of-call context, so it stops short of a 5.

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?

A single sentence, front-loaded with the scope ('for one capability') and then the return contents; every clause carries information. Slightly dense as a comma-listed enumeration, but no filler.

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 single-parameter, read-only tool with no output schema, the description covers both the input scope and the shape of the returned comparison. Nothing essential is missing, though it does not say how many tools are compared or how results are ordered.

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 schema already explains that the capability may be a slug or a resolvable phrase. The description's example slugs ('youtube-thumbnails', 'crm-contacts') are mildly illustrative but largely restate what the schema provides, so the baseline of 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 (all known tools for one capability), with concrete capability examples that pin down the scope. It is distinguishable from siblings like find_alternatives or search_catalog by the exhaustive 'all known tools' framing, though no sibling is named explicitly.

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 phrase 'For one capability' implies when the tool applies, but there is no explicit when-to-use/when-not guidance and no routing to alternatives such as find_alternatives or recommend_stack, which cover adjacent intents. Usage is inferable rather than stated.

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