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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, so the mutation/repeatability profile is covered. The description usefully adds the input domain limits and states the result shape (model plus fit evidence), but omits cost/auth context despite the const max_total_price of 0.005000 implying a paid job.

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 Problem/Input/Result/Limits format is front-loaded and efficient, with the core operation stated first. No wasted sentences, though the terse label style sacrifices some clarity.

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 need not be explained, and the description covers input composition and limits. But for a 4-param, nested-object, paid job at 0% schema coverage, it leaves gaps around the wrapper parameters and cost/auth expectations.

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% with 4 params, so the description must carry the burden. It partially does by specifying that the request JSON holds feature count, output count, features, and targets, but the other required fields (schema_version, idempotency_key, max_total_price) get no semantic explanation.

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 names a specific verb (Fit) and a concrete resource (a bounded structured quaternion ridge model over coupled channel features/targets), which is distinguishable from siblings like extract_wave_features or optimize_processing_pipeline. However, the jargon ('structured quaternion ridge') and lack of explicit sibling comparison keep it from 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?

No statement of when to use this tool versus the many other wave_* fitting/processing siblings, and no prerequisites or exclusions. The 'Limits' line gives operating constraints (bounded signal processing, 16 channels, 512 samples/channel) but that is scoping, not usage guidance.

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