gmail_modifyThread

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

No annotations are provided, so the description must carry the full burden. It discloses that the operation modifies labels on all messages, but does not mention permission requirements, reversibility, error conditions, or whether existing labels are preserved. For a mutating tool, this is a significant gap.

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?

The description is a single declarative sentence that precisely conveys the tool's action and scope. There is no redundant wording or extra content.

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?

The tool is a mutation with no output schema and no annotations. While the purpose and parameters are clear, the description does not explain the return value, error behavior, or permissions. For a thread-level mutation with no output schema, this information is necessary for safe and 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?

The input schema provides complete descriptions for all three parameters (threadId, addLabelIds, removeLabelIds), with 100% coverage. The description adds no parameter-specific semantics beyond what the schema already states, so baseline 3 is appropriate.

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 uses a specific verb ('Modify') and resource ('all messages in a Gmail thread'), clearly distinguishing it from sibling tools like gmail_modify (single message) and gmail_batchModify (arbitrary message IDs). The scope is explicit.

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 implies the use case: applying label changes to an entire thread at once. This provides clear context for when to use it, though it does not explicitly name alternatives or state when not to use it. Sibling tools like gmail_modify are not referenced.

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