echo

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

With no annotations, the description carries the full behavioral burden. It fully discloses the input mechanism, the output mechanism, and the absence of side effects inherent in echoing arguments back. It also explains the stdin/stdout contract, which is beyond the bare tool name.

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?

Two sentences with no waste: the first states the core behavior, and the second provides useful protocol context. The most important information is front-loaded.

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?

This is a low-complexity tool with no output schema, and the description fully covers its behavior, I/O contract, and purpose. An agent has everything needed to call it correctly.

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 schema declares no properties but allows additional properties, and the description refers generically to 'tool arguments,' which is sufficient for a tool that simply mirrors whatever it receives. With a zero-parameter baseline, the description does not need to document individual parameters.

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 opens with a specific verb and resource: 'Echoes the tool arguments back as JSON.' This clearly identifies what the tool does and distinguishes it from the clock and get-policy siblings, which do not echo input.

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 use as a demonstration or contract-verification tool by saying it 'Demonstrates the Ephemora Cell MCP stdin/stdout contract.' It does not explicitly state when not to use it, but the echo behavior is self-evident and no sibling tool is a realistic alternative.

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