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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so safety is covered. The description adds genuinely useful non-annotation context: this is a deprecated/legacy alias kept for backward compatibility, and its return format differs from `search`. It does not detail the actual return shape, pagination, or result cap, which keeps it short of 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?

Front-loaded with the legacy/deprecation status, then the behavioral difference, then the routing advice — a sensible order. It is slightly padded by the long quoted site name, but every sentence carries information.

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 two-parameter, deprecated read tool with no output schema, the description supplies what an agent most needs: it is legacy, prefer `search`, and the return format differs. The omission of any detail on that differing return format is the main residual gap.

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 only 50% (query is documented in-schema, `limit` is not), and the description adds no parameter information at all — it never explains the result cap, default of 5, or what `limit` controls. With low coverage the description is expected to compensate, and it does not.

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 action — it searches within the site (サイトの中を探す) — and explicitly frames itself as a legacy alias of the sibling tool `search` that returns a different shape. An agent can distinguish it from `search` without opening the schema, though the 'former name of the function' framing is slightly indirect about what the tool itself does.

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 (retained only for users already connected to it) and a clear alternative ('新しく使うときは search を使ってください' — use `search` when starting fresh). This is a textbook routing instruction with the alternative named and the selection condition stated.

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