update_rule

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

Adds useful behavioral details: timestamped backup before writing and potential need to restart Mail.app, complementing annotations that indicate modification but non-destructive.

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?

Two concise sentences cover purpose, prerequisite, and two behavioral notes with no unnecessary words.

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?

Covers key aspects: purpose, prerequisite, backup, restart. Lacks mention of the response (no output schema), but overall sufficient given complexity.

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 100%, so the schema already explains parameters well. The description adds little beyond what's in the parameter descriptions, meeting the baseline but not exceeding.

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?

Clearly states updating an existing Mail.app rule by RuleId, referencing list_rules for finding IDs, distinguishing it from sibling tools like create_rule.

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?

Mentions prerequisite (use list_rules to find IDs), but does not explicitly exclude when not to use or contrast with alternatives like create_rule or delete_rule.

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