get_messages

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

With no annotations, the description must disclose behavioral traits, but it only states that it returns a list of message dicts 'possibly of length 0 or 1'. This is misleading for multiple message IDs, and it fails to mention side effects, cost, or performance considerations. It also doesn't warn about heavy payloads from full details, leaving the agent without critical behavioral expectations.

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 compact (two sentences) and front-loaded with the main purpose. However, the phrase 'possibly of length 0 or 1' is not only ambiguous but also potentially incorrect for multiple IDs, which detracts from an otherwise tightly written definition.

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 parameter schemas are rich, the description provides useful context on usage and alternatives. However, the misleading return-length statement creates incompleteness, and it does not mention that multiple IDs yield multiple results or that results are partial if some IDs are missing (though the schema does). This leaves the description slightly incomplete.

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%, so the baseline is 3. The description does not add meaning to parameters beyond what the schema already provides. It doesn't compensate for any gaps, but since none exist, the score remains at the baseline.

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 verb 'Get', the resource 'messages', and specifies 'full details with bodies'. It explicitly differentiates from siblings by naming 'search_messages' as metadata-only and 'get_thread' as thread member ids, making the tool's unique role unambiguous.

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 explicitly pairs with 'search_messages' and 'get_thread' and states that this tool fetches bodies for specific messages, implying when to use it versus alternatives. This gives clear context and a specific condition (need bodies) that selects this tool.

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