fmsg-mcp

List inbox

list_messages

Read-onlyIdempotent

Retrieve messages received by an address, newest first, showing sender, topic, read state, size, attachments, and previews. Filter unread or include reactions to scan an inbox.

Instructions

List messages received by this address, newest first. Each item carries the id, sender, recipients, topic, time, read state, flags, size, attachment names and types, and a short preview. Reaction messages are hidden unless include_reactions is true, and hidden reactions never count as unread; listed reactions have their own read state (mark_read accepts them) and carry the emoji in reaction. Topics are set only on a thread's first message; get_thread reports a reply's thread_topic. Use get_message for a full body and get_thread for the conversation around a message.

Input Schema

TableJSON Schema

Name	Required	Description
`limit`	No	page size (host maximum 100)
`offset`	No	number of newest messages to skip
`unread_only`	No	keep only unread messages from the fetched page (reactions only with include_reactions)
`include_reactions`	No	also list reaction messages (normally hidden)

Output Schema

TableJSON Schema

Name	Required	Description
`count`	Yes
`offset`	Yes
`messages`	Yes
`next_offset`	Yes	offset for the next page, or null when this page was short
`untrusted_content_notice`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed13 schema fields changedv1.1.0Oct 15, 2026

addedInput schema / additionalProperties
```
Added value: +false
```

changedInput schema / properties / unread_only / description

Previous value: -"keep only unread messages from the fetched page"New value: +"keep only unread messages from the fetched page (reactions only with include_reactions)"

changedOutput schema / additionalProperties
```
Previous value: -falseNew value: +{}
```
changedOutput schema / properties / messages / items / additionalProperties
```
Previous value: -falseNew value: +{}
```
addedOutput schema / properties / messages / items / properties / attachments / description
```
Added value: +"sorted by filename, the same order in every tool"
```
changedOutput schema / properties / messages / items / properties / attachments / items / additionalProperties
```
Previous value: -falseNew value: +{}
```

addedOutput schema / properties / messages / items / properties / attachments / items / properties / type

Added value: +{
+  "description": "media type; inferred from the filename when the host records none",
+  "type": "string"
+}

addedOutput schema / properties / messages / items / properties / compressed

Added value: +{
+  "description": "true when the body was sent deflate-compressed on the wire (see size)",
+  "type": "boolean"
+}

addedOutput schema / properties / messages / items / properties / preview / description
```
Added value: +"start of the body; may be shorter than the full body"
```

addedOutput schema / properties / messages / items / properties / reaction

Added value: +{
+  "description": "the emoji when this message is itself a reaction (\"\" clears one); null otherwise",
+  "type": [
+    "string",
+    "null"
+  ]
+}

changedOutput schema / properties / messages / items / properties / reactions / items / additionalProperties
```
Previous value: -falseNew value: +{}
```

addedOutput schema / properties / messages / items / properties / size / description

Added value: +"body size in bytes as stored by your host: for a message you received with compressed true, the compressed wire length; your own sent messages store the uncompressed length. body_bytes, where given, is the decoded length"

addedOutput schema / properties / untrusted_content_notice
```
Added value: +{
+  "type": "string"
+}
```

First observedv0.1.3Sep 5, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Beyond the readOnly/idempotent/non-destructive annotations, it discloses non-obvious behavior: reactions are hidden by default, hidden reactions never count as unread, listed reactions carry their own read state and are accepted by mark_read, and thread topics live only on a thread's first message. This is exactly the operational nuance annotations cannot express.

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

Conciseness4/5

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

Front-loaded with purpose and ordering, then behavior, then routing to siblings. Three dense sentences that mostly earn their place; enumerating every returned field is somewhat redundant given an output schema exists, but it remains scannable.

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 tool with annotations covering the safety profile and an output schema covering return shape, the description still supplies the reaction-family semantics and sibling routing an agent needs to call it correctly. No meaningful gap remains.

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 100%, so the baseline is 3. The description adds meaning on top of the schema: the unread/reaction interaction ("hidden reactions never count as unread") and the emoji payload in reaction messages, which the schema's terse flag descriptions do not fully convey.

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?

States a specific verb and resource ("List messages received by this address") plus ordering ("newest first"), which cleanly separates it from the sibling list_sent. An agent can pick this without opening the schema.

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 routes to alternatives with conditions: "Use get_message for a full body and get_thread for the conversation around a message." It also states the condition that governs reaction visibility (include_reactions). Nothing about when to choose this tool is left to inference.

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

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