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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-structured context: the tool is deprecated and retained only for backward compatibility, and it diverges from `search` in return format. It stops short of saying how the format differs or noting pagination/limit behavior.

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?

Two tight sentences plus a parenthetical; the deprecation notice is front-loaded and the redirect to `search` lands last, which is the right ordering. The parenthetical about the site name is slightly more context than strictly needed but earns its place by identifying the resource.

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?

There is no output schema, so the description carries some return-value burden; it flags that the shape differs from `search` but never describes it. For a low-complexity legacy alias whose main decision (avoid unless already integrated) is fully answered, this is adequate but not complete.

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?

With only 50% schema description coverage, the `limit` parameter (default 5, max 20) is documented nowhere, and the description says nothing about parameters at all — no syntax, no effect of `limit`, no query-format hints. The description fails to compensate for the coverage gap.

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 concrete verb and resource (site-wide search) and explicitly frames itself as the legacy name of the site-search function, naming the sibling `search` as the equivalent. It distinguishes itself from that sibling by noting a different return shape, though it defines its own behavior only relationally to `search` rather than describing the output itself.

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 gives an explicit when-to-use (only for integrations already wired to it) and an explicit when-not-to-use with the named alternative: '新しく使うときは search を使ってください' (use search for new work). The agent has no inference left to make about tool selection.

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