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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely new behavioral context: the operation is non-persisting, invalid input does not raise but returns {valid: false, errors}, and violations are reported per-item with loc/msg. The 'verdict is data, never an exception' clause is a valuable, non-obvious contract that annotations cannot express.

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 tightly written sentences, front-loaded with the core action and non-persistence, then the return contract. Every clause carries information and nothing is wasted.

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?

With annotations, a fully described single parameter, and an output schema already present, the description supplies the remaining behavioral context an agent needs (non-persistence, error-as-data). Only the lack of explicit alternative routing (e.g., pointing at protocol.save) keeps it from being fully self-sufficient.

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?

Only one parameter (spec) exists and schema description coverage is 100%, so the schema already documents its shape in detail (id, name, indicator, armDefaults, blocks, threshold, sessions, breakCriteria). The description adds nothing beyond what the schema provides, making the baseline 3 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?

States a specific verb (validate) and a specific resource (neurofeedback protocol document), and the phrase 'WITHOUT saving it' immediately distinguishes it from the sibling protocol.save. An agent can identify this tool's role without opening any 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?

The non-persisting nature ('WITHOUT saving it') clearly frames this as a pre-save/dry-run check against protocol.save, which is strong contextual guidance. It stops short of explicitly naming the alternative or stating when-not to use it, so it lands just below the top tier.

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