gmail_apply_labels

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

Annotations already declare the safety profile (not read-only, idempotent, not destructive), so the bar is lower. The description usefully adds that TRASH is protected and routed elsewhere, but omits other behavior that matters for a mutation tool: whether unknown label names are created or error, whether add/remove can be combined in one call, and permission requirements.

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 short sentences with the core action front-loaded and the safety caveat second; nothing is padded. It is arguably too terse given the undocumented parameters, but every sentence earns its place.

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 4-parameter mutation tool with no output schema and zero schema descriptions, the definition leaves too much unexplained: label identifier format, message-vs-thread targeting, and what a successful response contains. Only the TRASH restriction is covered.

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% for 4 parameters, so the description must carry the burden and largely does not. It never explains 'id', the 'type' enum (message vs thread, defaulting to message), or the label-name-vs-ID format and 100-item cap on add_labels/remove_labels.

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 verb and resource ('Adds and/or removes Gmail labels'), which is clearer than the bare tool name. It also carves out TRASH as out of scope, hinting at a boundary with siblings, but it never distinguishes itself from gmail_batch_modify_labels, the closest alternative.

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?

One explicit exclusion is given: TRASH must go through gmail_trash_message. However, there is no guidance on when to use this single-item tool versus gmail_batch_modify_labels, nor on prerequisites such as whether the label must already exist.

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