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

The annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: no login or payment required, no generative AI involved, a hard cap of two rivals, and an explicit post-call flow (show results to the user, then point to how_to_start). It does not discuss failure modes for unreachable sites, which keeps it at 4.

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 action and comparison scope, followed by constraints and then the follow-up instruction. Every clause carries information an agent needs; nothing is redundant.

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 must convey what comes back, and it enumerates the compared dimensions, so the agent knows what to report. It stops short of describing the result's shape (e.g., per-site breakdown vs. side-by-side summary), a minor gap for a read-only comparison tool.

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 the schema already carries the meaning of site, rivals (max two) and the optional agent name. The description only echoes the 'two places maximum' limit for rivals and adds nothing about address format or the quota effect of the agent field. 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 and resource: read my homepage and up to two rivals' homepages once and compare title, promo/event copy, menu, posts from the last 30 days, and KakaoTalk channel presence. The comparison scope and item list distinguish it clearly from the sibling how_to_start, which is named as the follow-up tool.

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?

Establishes the usage context (one-shot first-screen comparison, no login, no cost) and explicitly routes the agent to how_to_start when the user wants ongoing monitoring. It does not state when *not* to use it or what to do if a site cannot be read, so it falls just short of a full when/when-not/alternatives statement.

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