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

Annotations already cover the safety profile (destructiveHint=false, openWorldHint=false), so the bar is lower; the description adds cost context ('FREE') and carbon-only scope. However, it never reconciles why a pure ranking operation carries readOnlyHint=false, which an agent could reasonably read as hidden state changes.

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 dense sentences with the value proposition front-loaded and no filler. Minor cost: the 'FREE:' prefix and the cryptic 'GR6' token consume attention without being self-explanatory.

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?

An output schema exists, so return values needn't be spelled out, and the description correctly stays high-level there. But for a tool whose required parameter is a free-form nested object, leaving the workload contract entirely undefined is a meaningful gap for correct invocation.

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 0% and the description does not compensate: 'workload' is an untyped object with additionalProperties=true and its expected shape is never hinted at. 'Eligible path' faintly implies allowed_backends acts as a filter, but neither parameter's format or accepted values are explained.

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?

States a specific verb and resource — 'rank compute backends by carbon for this workload' — and even names the output shape (greenest eligible path plus gCO2e saved per call). It does not explicitly distinguish itself from the closest siblings (quote_footprint, list_green_certificates), so it falls short of a 5.

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?

'Carbon only (GR6); pair with /neurogenesis/mcp route_task for quality-floor routing' tells the agent when this tool is the right choice and names an alternative plus the condition that selects it. It gives no guidance on when NOT to use it versus the carbon siblings like quote_footprint.

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