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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine behavioral context beyond that: results are curated rather than computed, ordering mirrors the web path /alternatives/{slug}/, and the output is factual rather than evaluative. It does not say what happens for an unknown slug or how results are ordered internally.

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 trigger condition, then the return content, then an important semantic caveat. Nothing is redundant or padded.

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 simple read-only lookup with full schema coverage and rich annotations, the description supplies what the schema cannot: the nature of the returned list and its ordering. It leaves open how the tool resolves requests when neither optional parameter is supplied and what an unknown slug yields, which is a modest gap rather than a blocking one.

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% and both parameters already carry descriptions ("Agent slug, e.g. vanta", "Agent or vendor name, e.g. Vanta"). The description adds only a weak hint via the /alternatives/{slug}/ reference, but never clarifies the relationship between the two optional parameters or which one drives resolution. Baseline 3 is appropriate.

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?

"Returns the curated alternatives list for that listed agent" states a specific verb (returns) and resource (alternatives list for an agent), and "Facts only — not a ranking or recommendation" implicitly separates it from the comparison-flavored sibling compare_agents. An agent can tell what this produces without opening the schema.

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?

"Use when the user asks for alternatives to a named vendor (e.g. Vanta, Drata)" gives a concrete trigger condition with examples. The exclusion is only implicit ("not a ranking or recommendation" implies compare_agents is for comparisons); no explicit when-not-this statement is given.

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