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 a genuinely useful trait beyond them: the return shape differs from `fetch`, which matters for callers parsing the result. It stops short of saying what that shape actually is.

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 sentences that each carry content (deprecation status, behavior, alternative), but the opening sentence about the legacy product name is largely historical context that a new caller gains little from. Front-loading the 'use fetch instead' guidance would serve the agent better.

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, and the description only says the returned shape "is different" from `fetch` without describing it, leaving the actual response format undocumented. Adequate for a deprecated shim whose users are told to migrate, but not complete on the one thing distinguishing it.

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 100% for the single `url` parameter, including the note that paths and Japanese characters are accepted. The description adds nothing about the parameter, so the baseline of 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?

The description states the action plainly ("fetch と同じようにページの本文を返します") and identifies it as a legacy alias of the codenate.jp feature, distinguishing it from the sibling `fetch` by noting the return shape differs. The framing leads with deprecation/identity rather than the verb+resource, so it is clear but not maximally direct.

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 and the condition selecting it: retained only for users already connected under the old name, and "新しく使うときは fetch を使ってください" tells new callers to use `fetch` instead. No inference required about when to choose this vs. a sibling.

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