gmail_messages_list

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

Annotations declare readOnlyHint=true, so the agent knows it's safe. However, the description adds no additional behavioral details like pagination limits, default maxResults, or that it returns message IDs/snippets rather than full bodies. For a list tool with no output schema, more transparency is needed.

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?

Single sentence, no filler, perfectly concise. Every word earns its place.

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?

The tool has no output schema and 4 parameters. The description does not explain what the response contains (e.g., list of message resources, metadata only). For a list operation, this is a significant omission that forces the agent to assume based on analogies. Does not fully cover the tool's behavior.

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?

The input schema already has 100% coverage with clear descriptions for all 4 parameters (q, userId, labelIds, maxResults). The description adds no further semantic value beyond restating the filter capability. 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 the tool lists Gmail messages filtered by a query, with a specific verb ('List') and resource ('Gmail messages'). It distinguishes from sibling tools like gmail_messages_get (single message) and gmail_threads_list (threads vs messages).

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?

No guidance on when to use this tool versus alternatives (e.g., gmail_threads_list for threads, gmail_messages_get for a single message) or when not to use it. The description lacks context about scope, such as that it returns message metadata, not full content.

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