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

Annotations already establish the read-only, idempotent, open-world safety profile, so the bar is lower. The description adds genuinely new behavioral context: a Watch subscription and key are required, the result is a 0-100 score benchmarked against the subscriber's own last weekly check, and it consumes/relates to the weekly check data.

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 dense sentence, front-loaded with the audience/key prerequisite and followed by the core action and the comparison output. Nothing is wasted, though the reference to 'the OperStack free check and the Watch email' is slightly indirect for an agent with no prior context.

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 no output schema, the description carries the burden of explaining the return value, and it does so by stating the score is out of 100 and is shown alongside the subscriber's own prior score. For a two-parameter read-only scoring tool this is largely sufficient, though it stops short of describing error/fallback behavior when no prior weekly check exists.

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%, so both parameters (url, site) are already documented with examples in the schema, making 3 the baseline. The description adds only marginal value, implicitly confirming that 'competitor site' maps to url and that a subscription may cover multiple watched sites.

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 and resource: it scores a competitor site out of 100 and places that next to the subscriber's own score. The 'same rules as the OperStack free check and the Watch email' phrasing clarifies how the score is derived, but it never names a sibling tool (e.g., compare_sites, audit_site, who_instead) that an agent might otherwise pick, so differentiation is implicit rather than explicit.

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 opening 'OperStack Watch subscribers, with their key' signals the audience and a prerequisite, which implies when the tool is applicable. However, there is no explicit when-not guidance and no named alternative for non-subscribers or for own-site checks, leaving the agent to infer that audit_site/compare_sites cover those cases.

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