Show one engine's input schema: required fields, units, alternative shapes, and a worked example. Always call this before run_engine unless you already know the schema — the engines reject bad input rather than guessing.
| Name | Required | Description | Default |
|---|---|---|---|
| engine | Yes | Engine id from list_engines. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It discloses what the tool returns and the important consequence that engines reject bad input, but it does not explicitly state that the operation is read-only or free of side effects, nor does it describe any auth or rate-limit behavior.
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 two tightly written sentences with zero waste. The core action and return contents are front-loaded, followed by the critical usage rule and rationale.
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?
For a simple one-parameter introspection tool with no output schema and no annotations, the description covers purpose, return contents, and the key usage relationship with run_engine. Nothing an agent needs in order to call it correctly appears to be missing.
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%, so the single 'engine' parameter is already fully documented in the schema as an engine id from list_engines. The description adds no additional syntax or format details about the parameter, so the baseline of 3 is appropriate.
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 states a specific verb ('Show') and resource ('one engine's input schema'), and enumerates the contents returned: required fields, units, alternative shapes, and a worked example. It also distinguishes this introspection tool from run_engine, making its role clear without opening the schema.
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?
It gives explicit when-to-use guidance: 'Always call this before run_engine unless you already know the schema.' It also provides the when-not condition (already knowing the schema) and the rationale (engines reject bad input rather than guessing), leaving nothing to inference.
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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