MCP Action Firewall

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

Without annotations, the description must carry the full disclosure burden. It identifies the returned content as an 'MCP logo image' and implies size with 'tiny', but omits critical behavioral details like return format (base64, binary, URL), content-type, or caching headers.

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 5-word sentence with zero redundancy. Every word earns its place, front-loaded with the action verb 'Returns'.

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 zero parameters, no annotations, and no output schema, the description adequately explains the core operation but lacks technical specifics (image encoding/format, MIME type) that would be necessary for an agent to properly handle the return value.

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?

Zero parameters are present, which per the rubric establishes a baseline of 4. The input schema is empty and correctly described by omission (no parameters to document).

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 specific verb 'Returns' and identifies the exact resource 'tiny MCP logo image'. It clearly distinguishes this from siblings like get-structured-content or get-env by specifying the MCP logo image content.

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?

No when-to-use guidance, prerequisites, or alternative tools are mentioned. The description states what the tool does but not under what circumstances to invoke it versus other resource-fetching siblings.

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