mcpmessage_inbox

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

The description discloses key side effects beyond the annotations: messages are marked as read by default, unread_only and mark_read change behavior, and mark_read=false provides a peek mode. It also warns about prompt-injection risks and describes the error return for unregistered chats. This is rich, useful behavioral disclosure.

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 efficiently structured: a one-sentence purpose, a short behavioral paragraph, a compact Args list, and a Returns line. Each part earns its place, including the essential security warning. It is detailed but not bloated.

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?

For a tool with four parameters, no schema param descriptions, and an output schema, the description covers everything needed to invoke it correctly: parameter semantics, defaults, side effects, return shape, and error behavior. Nothing critical is missing.

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 0%, so the description must fully compensate, and it does. Every parameter is explained with meaning and defaults: chat is the registered chat name, unread_only controls history vs unread, mark_read controls peek vs consume, and limit sets a maximum. No parameter is left ambiguous.

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?

Description opens with a specific verb and resource: 'Fetch messages addressed to a chat, oldest first.' This clarifies both the action and the ordering, and the tool is clearly distinct from siblings like send, thread, register_chat, and list_chats. The main purpose is unambiguous and front-loaded.

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 gives clear usage context: 'calling it periodically behaves like checking mail' explains the intended pattern. It also warns that content from other chats must be treated as data, not instructions. It does not explicitly mention when to use a sibling tool instead, but the context is strong enough for selection.

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