gmail_modify

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

Annotations already establish readOnly=false, openWorld=true, destructive=false. The description adds genuine behavioral context beyond them: 'archive (remove from inbox)' clarifies what archiving actually does, and 'New labels are created automatically' discloses a non-obvious side effect. It omits permissions, idempotency, and error behavior, so not 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?

Two tight sentences, operations front-loaded, zero filler. The side-effect note about labels is placed last as a secondary detail, which is correct prioritization.

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 mutation tool with annotations covering the safety profile, the description adequately covers what changes are possible, but it says nothing about return values (no output schema) or failure behavior for invalid/over-limit ids. Enough to invoke, not enough to fully predict the result.

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 only 50%, and the description compensates: star/unstar maps to 'starred' and add/remove labels map to the two label arrays, none of which have schema descriptions. It doesn't add syntax or format detail, but it does recover the meaning of the undocumented parameters, pushing it above baseline.

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 ('Change messages') plus a concrete enumeration of operations (read/unread, star/unstar, archive, add/remove labels), so an agent can tell what it does without opening the schema. It doesn't explicitly differentiate from adjacent siblings like gmail_trash or gmail_mark_spam, which keeps it just short of a 5.

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?

The description lists capabilities but gives no when-to-use guidance, no prerequisites, and no routing to alternatives. An agent must infer from the operation list that this is for bulk attribute edits rather than trashing or spamming.

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