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

Annotations already declare idempotent=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely new behavioral context the annotations don't carry: the lease-ownership authorization requirement and the fact that no new message is dispatched. It omits platform-level caveats (e.g. Telegram edit windows or re-edit semantics), keeping it just 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?

Three short sentences with zero filler: action, provenance of the ID, explicit non-effect, and the authorization constraint. The most decision-relevant facts are front-loaded.

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?

With annotations covering safety and idempotency, a complete schema, and no output schema requiring explanation, the description supplies what's missing: the lease requirement and the no-new-send guarantee. What remains unexplained — failure modes or whether prior text is recoverable — is minor for a non-destructive, idempotent edit.

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%, so all three parameters (text, message_id, parse_mode) are already documented, and parse_mode has an enum. The description adds only the provenance hint for message_id ('from line_send or line_inbox'), which is useful but marginal against a fully documented schema — 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?

Names a specific verb (edit) and resource (text of a message this line previously sent), plus the scope qualifier 'this line sent earlier' and the platform (Telegram). It also pre-empts confusion with the larger send family by stating 'Nothing new is sent,' so an agent can distinguish it from line_send without opening a schema.

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 routes the agent to line_send or line_inbox as the source of message_id, and states the hard prerequisite that only the cable holding the line's lease can edit. It stops short of naming the alternative tool to call when a new message is actually wanted, so the 'when not to use' side is only implied by 'Nothing new is sent.'

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