Email Get Messages

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety is covered. The description adds valuable behavioral context by noting that missing IDs yield an error entry, which is not captured by annotations. It also implies a performance benefit (one round trip) without contradicting 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?

Two concise sentences with no fluff. The primary purpose is front-loaded, and the error behavior is stated in a second sentence. Every word earns its place, and the description is easily skimmable.

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 output schema exists and the parameter schema covers all inputs, the description is adequate. It addresses the key differentiator (batch) and a potential failure mode (missing IDs). No critical information is missing for an agent to call this tool correctly, though it could mention that IDs must belong to the same folder, but that is already in the schema.

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 each parameter described in detail, so the description adds little beyond referencing the return fields. It does not clarify parameter semantics beyond what the schema already provides, so the 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 fetches multiple messages in a single round trip, referencing the singular email_get_message to indicate identical return fields. It distinguishes itself from the sibling email_get_message by the explicit batch nature, leaving no ambiguity about what it does.

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 phrase 'several messages in one round trip' implies the tool is for batch retrieval, and the reference to email_get_message suggests that tool is for single messages. However, it does not explicitly state 'use email_get_message for a single message' or provide exclusions, though the openWorldHint annotation adds context that any input is acceptable. The guidance is clear but not exhaustive.

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