List Gmail messages that match a search query, with optional label filters and result limits, to retrieve specific emails from a user's mailbox.
List Gmail messages matching a query.
| Name | Required | Description | Default |
|---|---|---|---|
| q | No | Gmail search query (e.g. "from:user@example.com subject:hello") | |
| userId | Yes | User ID (use 'me') | |
| labelIds | No | Label IDs to filter by | |
| maxResults | No | Max messages to return |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnlyHint=true and openWorldHint=true, so safety and open-ended queries are known. The description adds nothing about pagination, response contents, or whether it returns full messages or summaries. Minimal added value beyond the 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?
A single sentence with zero redundancy. The action is front-loaded and the meaning is clear. Perfectly concise for the information it conveys.
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 4 parameters, all documented in the schema, and no output schema. The description doesn't clarify what the response contains (e.g., message summaries, pagination tokens), which could surprise an agent. Given moderate complexity and a list operation, more detail would help, but annotations cover the read-only nature.
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?
All four parameters are fully described in the input schema (100% coverage), so the description need not repeat parameter details. The description doesn't mention parameters at all, but the schema carries that burden, making the baseline 3 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?
States a specific verb (List) and resource (Gmail messages) with a query condition. It is distinct from siblings like gmail_messages_get (singular) and gmail_threads_list (threads), though it doesn't explicitly contrast them. The core purpose is 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?
No guidance on when to use this tool versus alternatives like gmail_threads_list or gmail_messages_get. There is no mention of use cases, prerequisites, or typical scenarios. The agent gets no direction on selection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.