Mock MCP Server

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

No annotations are provided, so the description carries the full burden. It states the tool 'echoes back' the message, which implies a read-only or non-destructive operation, but doesn't disclose details like whether it modifies the input, requires authentication, has rate limits, or what the output format is. The description is minimal and lacks behavioral context beyond the basic action.

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 with no wasted words, clearly front-loaded with the core action. It's appropriately sized for a simple tool, making it easy to scan and understand quickly.

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 (1 parameter, no annotations, but has an output schema), the description is complete enough for basic use. The output schema likely handles return values, so the description doesn't need to explain them. However, it could benefit from more behavioral context, but for this simple case, it's adequate.

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 1 parameter with 0% description coverage, so the schema provides no semantic details. The description adds meaning by specifying that the parameter is a 'message' to be echoed back, which clarifies its purpose beyond the schema's type definition. However, it doesn't detail constraints or examples, but with only 1 parameter, this is sufficient for baseline understanding.

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 'Echo back the provided message' states what the tool does with a clear verb ('echo back') and resource ('message'), but it's somewhat vague as 'echo' could imply various behaviors like returning the exact input or processing it. With no sibling tools, differentiation isn't needed, but the purpose could be more specific about the exact behavior.

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 no guidance on when to use this tool versus alternatives, as there are no sibling tools mentioned, but it also lacks context on prerequisites or typical use cases. It's a basic tool with implied usage for testing or debugging, but no explicit guidelines are given.

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