Geppetto Robot Directory

Compare Two Robots

compare_robots

Read-onlyIdempotent

Compare two robots side by side on specs, price, and capabilities. Returns a comparison URL and key differences.

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": {
      "robot_a": "<robot_a>",
      "robot_b": "<robot_b>"
    },
    "name": "compare_robots"
  }
}

Input Schema

Name	Required	Description	Default
`robot_a`	Yes	First robot slug
`robot_b`	Yes	Second robot slug

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 13, 2026

TDQS

A3.6/5.0

Behavior3/5

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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds useful output framing (a comparison URL plus key differences), which matters given there is no output schema, but it says nothing about failure behavior for invalid or identical slugs.

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

Conciseness5/5

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

Two short sentences, zero filler, with the core action front-loaded and the return value following. Nothing in the text could be removed without losing information.

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 simple two-parameter read tool, the definition covers what it does and what comes back, which compensates for the absent output schema. Only edge-case handling (invalid slug, same robot twice) is left unspecified, a minor gap at this complexity.

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 100% and both properties are documented as robot slugs, so the schema does the heavy lifting. The description adds no further meaning about slug format, ordering effects, or whether order matters for the returned comparison.

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?

"Compare two robots side by side on specs, price, and capabilities" is a specific verb-plus-resource statement that also scopes what is being compared. It is implicitly distinguishable from the single-robot sibling get_robot, though no sibling is named explicitly.

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?

Usage is only implied by the word "compare" and the two required robot arguments; an agent can infer this is the multi-robot lookup versus get_robot. There is no explicit when-to-use or when-not-to-use guidance, nor any note that the two slugs should differ.

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

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