mcp-server-scaffold

echo

Repeats a message back to the caller, optionally converting it to uppercase, so developers can verify a working MCP tool and test stdio JSON-RPC responses.

Instructions

Repeats your message back, optionally shouting (uppercase). The simplest example of a working MCP tool.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "message": "<message>"
    },
    "name": "echo"
  }
}

Input Schema

Name	Required	Description	Default
`shout`	No
`message`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Nov 1, 2026

TDQS

A3.5/5.0

Behavior3/5

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

With no annotations, the description carries the full burden, and it does disclose the one behavioral variation (uppercasing when shout is set). It does not state that the call is side-effect free, non-persistent, or what exactly is returned (string verbatim vs. wrapper), which matters given there is no output schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, front-loaded with the core behavior and the optional flag. The second sentence is meta-commentary about being an example tool — mildly useful for intent, but not essential to invocation.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter, no-annotation, no-output-schema tool the description is close to sufficient: the agent knows the input transformation and the return concept. Missing only the echo-is-not-persisted and length-limit details.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0%, so the description must compensate; it usefully explains shout as "uppercase", which the schema does not. However, the required message parameter and its 2000-character limit (which would cause a validation error) are not mentioned, leaving a gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

"Repeats your message back, optionally shouting (uppercase)" states a specific action and its single transformation variant, so an agent knows exactly what the tool produces. It never names the sibling note_write or states that nothing is persisted, which is the only real distinguishing fact an agent might need.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit when-to-use, when-not, or alternative is given. "The simplest example of a working MCP tool" only implies a demo/smoke-test role, and the agent must infer that from framing rather than from stated guidance.

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

Deploy Server

Other Tools

echoA
note_writeB