gmail_threads_modify

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

Annotations already signal mutation (readOnlyHint=false), idempotency, and non-destructive behaviorhol. The description adds behavioral value beyond that by telling agents exactly how to achieve side effects like archiving and starring, which is useful operational context not captured in the annotations.

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 short sentences, zero filler. The purpose statement is front-loaded Illustration followed directly by the most useful examples. 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 simple label-modification tool with 100% schema coverage and meaningful annotations, the description covers the core operational context. It does not describe response values or mention that the modification applies to all messages in the thread, but the description and annotations together are sufficient for 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 100%, so the baseline is 3. The description goes further by explaining the semantic meaning of specific label IDs ('INBOX', 'UNREAD', 'STARRED') and how removing or adding them accomplishes user goals, making the parameters more actionable than the schema alone.

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 opens with a specific verb-resource pair ('Modify a Gmail thread') and immediately narrows the scope to add/remove labels. This clearly distinguishes it from read-only siblings like gmail_threads_get and gmail_threads_list.

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 gives practical usage context by mapping labels to common intents: 'To archive, remove INBOX. To mark read, remove UNREAD. To star, add STARRED.' It does not explicitly name alternatives or exclusions, but the examples effectively tell an agent when and how to invoke the tool.

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