create_rule

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

With no annotations, the description carries the full burden and does reasonably well: it discloses the future-mail-only scope ('Does not affect mail already received') and the concrete side effects for delete (Deleted Items) and junk (Junk Email). It omits permission/auth requirements, what happens on duplicate display names, and whether the created rule is returned, which keeps it 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 compact sentences, front-loaded with the core purpose, then conditions, then actions, then the scope caveat. No filler wording.

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 annotations and no output schema, the description covers the essentials: matching semantics, action-specific requirements, and side effects. Only the displayName/stopProcessingRules behavior and the return value are unexplained, a minor gap relative to the schema's own descriptions.

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 57%, and the description adds real meaning for destinationFolderId ('an id or a name like archive') and for the at-least-one-of constraint across the three condition arrays. However, displayName and stopProcessingRules (default true) are never mentioned in the description, leaving part of the gap unfilled.

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 and resource ('Create an inbox rule') plus the scope of what it acts on ('future incoming mail matching the conditions'). It is clearly distinguishable from the siblings list_rules and delete_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?

Gives a concrete precondition — at least one of fromAddresses, senderContains, subjectContains — and enumerates the four actions with their individual requirements (move needs destinationFolderId). It never explicitly names an alternative tool or a when-not-to-use case, but the conditions for correct invocation are unambiguous.

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