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

Annotations already indicate read-only, non-destructive, idempotent behavior. The description adds valuable behavioral details: message ordering (oldest-first), message structure (direction, id), truncation detection, and cross-reference to other tools for full bodies. No contradictions.

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 with no redundant information. The first sentence immediately states the core purpose and output structure. Subsequent sentences provide essential usage details. Efficiently 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?

Given the presence of an output schema (presumably detailing metadata and message fields), the description appropriately explains the thread structure, how to interpret completeness, and how to retrieve full message bodies. It leaves no critical gaps for a get-by-id tool.

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 100% with a clear description for the single parameter 'id'. The description reinforces the source of the ID (from any email or sent-email) and explains its role. This adds a helpful usage context beyond 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 clearly states the tool retrieves a conversation thread by ID, including metadata and all messages interleaved oldest-first. It specifies each message has direction and ID, and distinguishes from sibling tools like getEmail and getSentEmail by referencing them for fetching message bodies.

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?

Provides clear guidance on how to obtain the thread_id (from any email or sent-email record) and how to use the result (compare message_count vs messages.length for truncation, use getEmail/getSentEmail for bodies). Does not explicitly state when not to use this tool, but the context is sufficiently directive.

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