gmail_modify_labels

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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the description does not need to restate mutation. It adds useful behavioral mapping: removing INBOX archives and removing UNREAD marks read. This goes beyond the structured fields without contradicting them.

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?

A single action-first sentence with concrete examples, no filler, and no duplication of the schema's structure. Every word contributes to correct use.

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 simple three-parameter tool with no output schema, the description covers the core behavior, the required message context, and common label idioms. It omits edge-case details such as invalid label handling, but those are not necessary for basic correct invocation.

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 0%, but the description compensates by linking add/remove to label operations and by giving concrete label values like INBOX and UNREAD. 'On a message' implies that id is the message identifier, though the description could more explicitly state that add/remove expect label IDs.

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?

The description states a specific action ('Add or remove labels') and resource ('a message'), then grounds it in concrete Gmail intents (archive, mark read, triage). This clearly distinguishes it from sibling read/search/send tools.

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 phrase 'Use this to archive..., mark read..., or triage' explicitly signals when to invoke the tool. It does not enumerate alternatives or exclusion cases, but no close sibling performs label modification, so the usage context is clear.

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