apply_thread_action

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

Annotations provide destructiveHint: true, and the description adds context that actions are 'reversible' and supports dryRun for previewing impact. It also mentions scoping via unreadOnly and index refresh via syncBefore. This goes beyond the annotation without contradicting it.

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 sentences: purpose, usage, and alternative. Front-loaded with the essential description, no filler, 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 7-parameter tool with no output schema, the description covers the core action, use case, key scoping options, and alternative. It doesn't detail return values or failure mode, but the schema covers parameters and destructiveHint covers risk. Very solid overall.

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 high (86%) and all parameters have descriptions. The description reiterates dryRun, unreadOnly, and syncBefore but doesn't add new parameter-level meaning beyond what the schema already supplies. Minimally viable, not lacking but not additive.

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 ('Apply') and identifies the resource ('every message in a normalized thread'), immediately distinguishing it from single-message tools. It also names example actions ('archive or mark-read') and differentiates from batch_email_action by threadId vs emailIds.

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?

It explicitly states when to use the tool ('Use when you want to act on a full thread identified by threadId') and when to prefer an alternative ('Prefer batch_email_action when you have explicit emailIds rather than a threadId'). This gives clear decision guidance.

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