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

Annotations already declare readOnlyHint=true, destructiveHint=false and a closed world, so the safety profile is covered. The description adds valuable non-annotation context: this is a deprecated alias retained for backward compatibility and its output shape differs from fetch.

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?

Short and front-loaded with the most decision-relevant fact (legacy feature). The parenthetical domain and the duplicated deprecation messaging are slightly redundant but not wasteful.

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 single-parameter, read-only legacy tool with no output schema, the description says what it returns, how it differs from fetch, and why it exists. Nothing critical for a correct invocation is missing.

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?

Only one parameter with 100% schema coverage, including the note that Japanese URLs/paths are acceptable. The description adds nothing about the url argument, so the baseline 3 applies.

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+resource ('ページの本文を返す') and explicitly distinguishes itself from the sibling fetch by noting the return format differs. The legacy framing ('以前の名前の機能') is clear, though the identity of the tool is somewhat overshadowed by the deprecation notice.

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 names the alternative ('新しく使うときは fetch を使ってください') and the condition that selects it. It also explains why it still exists ('すでにつないでいる人のために残しています'), which tells the agent when NOT to pick it.

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