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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond the structured fields: this is a deprecated/legacy endpoint retained for backward compatibility, and its response format differs from the sibling 'search'. It does not detail the response shape or pagination, keeping it below 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?

Three compact sentences, front-loaded with the legacy-identity context and then the alternative. No filler, and the key routing advice lands before any secondary detail. Slightly more identity framing than strictly necessary, but it earns its place for disambiguation.

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 2-parameter, read-only, no-output-schema tool with annotations covering safety, the description conveys purpose, legacy status, and the sibling alternative. It leaves the undocumented 'limit' parameter and the nature of the differing return format unaddressed, which are the remaining gaps for an agent calling it correctly.

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 only 50%: 'query' is documented in the schema, but 'limit' (default 5, max 20, min 1) has no description anywhere. The description does not compensate for this gap – it says nothing about parameters, so the agent must infer 'limit' behavior from the raw schema constraints alone.

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 states a specific verb and resource (searches inside the site, like the sibling 'search' but with a different return shape) and clarifies that this is a legacy alias of the 'search' feature. An agent can distinguish it from 'search' without opening schemas. It stops short of a crisp standalone statement of what it does, since the 'former name' framing adds some ambiguity.

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?

It explicitly names the alternative ('新しく使うときは search を使ってください' – use 'search' for new usage) and gives the condition that selects it, plus the rationale for its continued existence (kept for already-connected users). This is exactly the when/when-not/alternative guidance the dimension rewards.

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