Element MCP Server

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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, and idempotentHint=true, covering safety and idempotency. The description adds valuable context beyond annotations: it specifies the return format (room IDs, names, topic, member count) and mentions the purpose of discovering rooms before fetching messages, which helps the agent understand the tool's role in a workflow. No contradictions with 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?

The description is front-loaded with the core purpose in the first sentence, followed by return details and usage guidance. Every sentence adds value: the first states what it does, the second specifies returns, and the third provides context for usage. No wasted words or redundancy.

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's low complexity (one optional parameter), rich annotations (covering safety and idempotency), and no output schema, the description is mostly complete. It explains the purpose, returns, and usage context. A minor gap is lack of explicit mention of pagination or ordering for the list, but annotations (openWorldHint=true) imply scalability, and the limit parameter handles basic control.

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 the single parameter 'limit' fully documented in the schema (type, range, default). The description does not add any parameter-specific information beyond what the schema provides, so it meets the baseline of 3 for high schema coverage without extra value.

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 specific action ('List all Matrix rooms') and resource ('that the user has joined'), distinguishing it from siblings like matrix_get_room_info (which likely gets details for a specific room) and matrix_search_messages (which searches messages rather than listing rooms). It explicitly mentions the verb 'list' and scope 'joined rooms'.

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 provides explicit guidance on when to use this tool ('to discover which rooms are available before fetching messages') and names a specific alternative ('Use room_id with matrix_get_messages to read messages'). It also implies when not to use it (e.g., for room details or message searching, handled by other siblings).

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