merge_email_threads

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

With no annotations, the description must disclose behavior. It states that messages and notes move from source to destination and marks the operation as [mutation]. The parameter description hints that the source thread is deleted. The description is clear but could mention additional side effects or reversibility.

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 sentences plus a mutation tag—no wasted words. Essential information is front-loaded.

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 description covers purpose, constraints, and required confirmation. Given no output schema, it is fairly complete, though it could mention error conditions or permissions. Overall adequate.

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?

All three parameters have schema descriptions (100% coverage). The tool description adds no extra semantics beyond the schema; it only repeats the confirmation requirement. Baseline of 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 clearly states the tool merges email threads, moving messages and notes from source to destination, and specifies the constraint of same email account. This distinguishes it from siblings like assign_email_thread or delete_email_thread.

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 includes a precondition (same email account) and a required confirmation parameter (confirm=true). However, it does not explicitly contrast with alternative tools for similar operations, leaving some ambiguity about when to use merge versus assign.

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