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

Annotations only declare destructiveHint=true, so the description does useful work by disclosing the instruction/run_hour coupling rule and the id source. However it never addresses mutation semantics — whether unspecified fields are preserved, what replacing a query does to existing behavior, or how much is destroyed under destructiveHint=true.

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 tight sentences with the field list and the two essential constraints (id source, coupling rule) front-loaded; no padding. The inline Japanese term 定期依頼 is mildly distracting but functions as a clarifying gloss rather than 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 7-parameter mutation tool with no output schema, the description covers the two things an agent would otherwise get wrong: where the id comes from and the instruction/run_hour dependency. It omits partial-update semantics (are unlisted fields cleared?) and account-list meaning, which is the main remaining gap.

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 71% and the description enumerates all seven fields (name, query, accounts, instruction, run_hour, enabled, plus the id), mapping them to colloquial names. The coupling constraint is the key semantic, though it is largely restated from the schema's own run_hour/instruction descriptions.

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 (Update) and resource (message alert / 定期依頼), then enumerates exactly which fields can be changed. It orients the agent by naming the sibling tools that produce the id (list_message_alerts) and define the query syntax (create_message_alert), so it is distinguishable without opening any 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?

Gives clear operational context: fetch the id from list_message_alerts, follow create_message_alert query conventions, and change instruction/run_hour together. It stops short of stating when to prefer this over create_message_alert/delete_message_alert, but the prerequisite and coupling rules make correct invocation inferable.

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