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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds legacy/deprecation status and that the return format differs from `search`, which is useful non-obvious context. It does not detail the actual return shape, but with annotations this is sufficient for a 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 concise sentences: identifies legacy status, explains similarity to `search` and the return shape difference, then gives routing advice. Front-loaded with what it is, though the full service name adds some verbosity.

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 deprecated search tool with no output schema, the description gives enough context: legacy status, alternative, and return format difference. However, it leaves the actual return shape unexplained, which could matter for existing users.

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 50%: the `query` parameter has a description in the schema, but `limit` has only type/default/min/max with no description. The tool description provides no additional parameter semantics or guidance, so it fails to compensate for the undocumented `limit` parameter.

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: searching within the site (サイトの中を探す), and explicitly identifies itself as the legacy name of a feature on the named service. It distinguishes from the sibling `search` by noting the return shape differs, so an agent can tell them apart without opening schemas.

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?

Explicitly states when to use this tool (for those already connected) and when not to (new use should use `search`), naming the alternative directly. The deprecation routing is unambiguous with no inference required.

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