proton-bridge-mcp

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List attachments

list_attachments

Read-only

List a message's attachments, separating real documents from inline images and PGP keys, to verify files before concluding a message has none.

Instructions

List a message's attachments, separating real DOCUMENTS from inline cid: images and PGP keys (hidden by default). Call before claiming a message has no attachment — read_message shows body text only and never reveals files.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "uid": "<uid>"
    },
    "name": "list_attachments"
  }
}

Input Schema

Name	Required	Description
`uid`	Yes
`folder`	No	Default INBOX.
`uidvalidity`	No	UIDVALIDITY reported alongside the uid. Pass it back so a mailbox resync cannot make this act on the wrong message.
`include_inline`	No	Also list inline images / PGP keys.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.2.1Aug 11, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Despite readOnlyHint and openWorldHint annotations, the description adds valuable behavioral context: it separates document types and hides inline cid: images and PGP keys by default. This goes beyond what annotations alone communicate and is crucial for correct invocation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences: the first front-loads the core purpose and key differentiation, the second provides a critical usage tip. No filler or repetition.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a list operation with no output schema, the description covers purpose, when to use it, an alternative, and unique behavioral quirks. It is sufficient for an agent to select and invoke the tool correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 75% (3/4 params documented). The description adds meaning for include_inline by explaining the default-hidden behavior and the document categorization, but does not elaborate on uid or folder beyond what the schema already states.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('list') and resource ('a message's attachments'), and further distinguishes itself by separating real documents from inline cid: images and PGP keys. This clearly differentiates it from sibling tools like read_attachment or view_attachment.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to use it ('Call before claiming a message has no attachment') and names the alternative (read_message) that only shows body text and never reveals files. This is direct, actionable guidance.

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