MCP Action Firewall

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. 'Echoes back' implies the operation returns the input unchanged (identity function), but the description omits whether this is read-only, if there are rate limits, payload size constraints, or the exact return format. It meets the minimum by stating the core behavior but lacks operational safety details.

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 of six words. It is front-loaded with the action verb and contains no redundancy or filler. Every word earns its place for this simple utility function.

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 this is a trivial single-parameter tool with complete schema coverage, the description adequately explains the operation (input reflection). However, it could improve by noting typical use cases (testing, debugging) or confirming the return behavior given the lack of output schema and annotations.

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% (the 'message' parameter is fully documented as 'Message to echo'). The description references 'input string' which aligns with the parameter, but adds no additional semantic value such as format constraints, encoding requirements, or validation rules. Baseline 3 is appropriate given the schema's completeness.

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 uses a specific verb ('Echoes') and resource ('input string') that clearly defines the identity operation. While it doesn't explicitly name siblings, the term 'echo' distinctively positions this as a simple reflection utility unlike the more complex retrieval or processing tools in the sibling list (e.g., get-annotated-message, simulate-research-query).

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. It does not indicate that this is typically used for connectivity testing, debugging, or validation versus actual message retrieval or processing tools.

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