Discord MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool retrieves a message with 'full attachment details', which adds some context about return content. However, it lacks critical behavioral information such as whether this is a read-only operation, potential rate limits, authentication requirements, error conditions, or what 'full attachment details' entails. This leaves significant gaps for an agent to understand the tool's behavior.

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 a single, efficient sentence that front-loads the core action ('Get a specific message by ID') and adds a key detail ('with full attachment details'). There is no wasted verbiage, and it directly communicates the tool's function without redundancy, making it highly concise and well-structured.

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 (2 parameters, no nested objects) and high schema coverage, the description is minimally adequate. However, with no annotations and no output schema, it fails to fully compensate for missing behavioral and output details. The mention of 'full attachment details' provides some output context, but without an output schema, this remains vague. The description is complete enough for basic understanding but lacks depth for reliable agent invocation.

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?

The input schema has 100% description coverage, with clear documentation for both parameters (channelId and messageId). The description adds no additional parameter semantics beyond what the schema provides, such as format examples or constraints. Since schema coverage is high, the baseline score of 3 is appropriate, as the description doesn't compensate but also doesn't detract.

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 verb 'Get' and the resource 'a specific message by ID', making the purpose evident. It distinguishes from siblings like discord_get_message_history (which retrieves multiple messages) by specifying retrieval of a single message. However, it doesn't explicitly contrast with discord_search_messages, which might also retrieve specific messages, leaving slight ambiguity.

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 usage when needing a single message with full attachment details, but provides no explicit guidance on when to use this versus alternatives like discord_get_message_history or discord_search_messages. It mentions 'full attachment details', which hints at a use case but doesn't state prerequisites or exclusions, leaving usage context partially inferred.

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