get_postal_thread

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, informing the agent of safe read behavior. The description adds the optional expansion of timeline events, which is valuable but not extensive. The behavioral burden is adequately covered by annotations.

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?

The description is two sentences: the first states the primary function, the second provides a use case. Every word is purposeful, no redundancy. It is front-loaded and efficient.

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 an output schema exists, the description does not need to explain return values. It covers the purpose, parameter functionality, and use case. The only minor gap is not mentioning that thread_id is a UUID, but the schema already provides format information. Overall, it is sufficiently complete for correct tool invocation.

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 detailed descriptions for both parameters. The tool description echoes the schema's mention of optional timeline events but adds no new semantic meaning. Baseline score 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 it retrieves a single physical-mail thread with optional timeline events, and specifies a distinct use case: explaining how outbound mail relates to prior inbound scans and decisions. This differentiates it from list_postal_threads and other sibling tools.

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 provides a specific scenario to use the tool, which guides the agent. However, it does not explicitly mention when not to use it or compare it to alternatives like get_inbound_mail or get_outbound_mail. The use case is clear but lacks explicit exclusions.

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