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 meaningful non-annotation context: it is a deprecated alias kept for backward compatibility and returns a different shape than search.

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-loads the deprecation/legacy status and the alternative, then adds the return-shape difference. Three compact sentences with essentially no filler.

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 legacy alias with full read-only annotations and no output schema, this is largely complete: it covers identity, relationship to `search`, and migration guidance. The one gap is that it says the return format differs without saying how, which matters when an agent must parse the result.

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 50%: `query` is documented in the schema but `limit` (default 5, max 20) is not. The description mentions neither parameter nor any query syntax or limit semantics, so it 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 this is the legacy-named feature that searches within the site, and explicitly distinguishes itself from the sibling `search` by noting the return shape differs. It is specific about verb and resource, though the title still labels it ambiguously as '以前の名前' (previous name).

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 routing directive: '新しく使うときは search を使ってください' (use search for new usages) and explains it is retained for existing integrations. That is clear when-to-use guidance, though it does not explain any scenario where this tool remains the correct choice.

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