imap_find_thread_messages

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

With no annotations provided, the description carries the behavioral disclosure burden. It reveals the underlying search method (RFC 3501 HEADER search on In-Reply-To and References), the compatibility guarantee ('works on any IMAP server'), and the round-trip optimization when `includeBody` is true. This goes well beyond a simple purpose statement, though it omits details about return format and failure modes.

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, all dense with useful information: the core operation, a practical use case, the technical mechanism, and the key optionality with its performance rationale. No filler or redundant verbiage.

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?

No output schema exists, so the description should clarify what the tool returns. It says 'found thread messages' and optionally 'parsed body', but does not describe the shape of the result set (e.g., array of headers, message objects, field names). The schema covers defaults and parameter richness well, but the output contract is a real gap for an agent. Thus not complete enough for a 4.

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% and the schema already explains all parameters, including `includeBody`'se N+1 benefit and `bodyFormat` behavior. The description mostly reinforces this same information rather than adding new parameter semantics. It does clarify the relationship between `sourceFolder` and `searchFolder`, but that is largely inferable from the schema too. 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 states a precise operation: find messages in `searchFolder` that belong to the same conversation threads as messages in `sourceFolder`. This clearly distinguishes it from general search tools like `imap_search_emails` or single-message lookup tools like `imap_find_email_by_message_id`, and it names the mechanism (RFC 3501 HEADER search).

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 a concrete use case: 'catching replies that arrived after a thread was sorted.' It also provides guidance on when to set `includeBody=true` to avoid N+1 round-trips to `imap_get_email`. However, it does not explicitly exclude alternative tools or state when not to use it, so it falls just short of a 5.

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