Read email thread

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

Read-only and idempotent behavior is already covered by annotations, and the description adds valuable behavioral detail: results always include the selected source, bounded results report hasMore/partial, and grouping is never by subject alone.

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 dense sentences with no filler. The main use case is front-loaded, and each clause contributes additional behavioral or scoping information.

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 and key result behavior, but with no output schema and four parameters it leaves parameter semantics and distinction from mail_get/search largely implicit. It is viable but not fully comprehensive.

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%, so the description must clarify parameters, but it only implies a selected source. id, limit, includeJunk, and includeTrash are not explained, leaving their semantics to inference from names and defaults.

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 action and resource: find messages within an email thread using Message-ID, References, and In-Reply-To headers. It also distinguishes behavior from subject-only grouping, which separates it from broader search siblings.

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 gives a clear call to action for thread retrieval and specifies the linking criteria. It does not name alternative tools or explicitly state when not to use it, but the intended context is evident.

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