List attachments for an email by message ID, downloading each to return its filename, MIME type, and size.
List attachments for an email message. Downloads all attachments to inspect them, then returns filename, MIME type (inferred from extension), and size for each.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Email message ID | |
| folder | No | Folder name (default: INBOX) | |
| account | No | Account name (uses default if omitted) |
Changes observed during successful MCP inspections.
v1.7.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description discloses that the tool downloads all attachments to inspect them, which is a notable side effect beyond listing. It also mentions that MIME type is inferred from extension, a limitation. No annotations are provided, so the description carries the full burden and does so adequately.
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, front-loading the purpose. It is concise without unnecessary words, though the second sentence could be slightly more efficient by omitting 'to inspect them' as it's implied.
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 tool has no output schema, the description adequately covers the return values and behavioral traits. It lacks mention of return structure (list vs. object) and error cases, but is sufficient for typical use.
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% with each parameter having a description in the schema. The tool description adds overall context but does not enhance parameter semantics beyond what the schema already provides.
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 attachments for an email message and specifies what it returns (filename, MIME type inferred from extension, size). This distinguishes it from sibling tool download_attachment, which downloads a single attachment.
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 implies use for inspecting attachment metadata but does not explicitly state when to use versus alternatives like download_attachment, nor does it mention exclusions or prerequisites.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.