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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description adds non-obvious behaviour beyond that: it returns "the likely cause, a concrete fix, and how to verify it," and defines the no-args index mode.

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?

Four front-loaded sentences that each carry information: purpose, return shape, topical coverage, and invocation. The topical enumeration is slightly list-like, but it helps the agent judge relevance, so it earns its length.

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?

There is no output schema, and the description compensates by summarising the return payload (cause, fix, verification). Combined with annotations covering the safety profile and an explicit no-args index mode, an agent has everything needed to call it correctly.

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 schema already documents every parameter (baseline 3). The description adds value by giving concrete example symptom values ("hydration mismatch", "value stopped updating") that illustrate free-text intent beyond the schema's generic wording.

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+resource: "Diagnose a client-side Nifra problem by symptom across every adapter." This is clearly distinct from sibling tools (nifra_docs, nifra_example, nifra_gallery, nifra_learn, nifra_types), which are reference/learning surfaces rather than a symptom-driven diagnostic. An agent can route to it 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?

Explicitly tells the agent how to invoke: "Call with no args for the index; pass symptom and/or adapter to filter," which resolves the ambiguity of a 0-required-param tool. It does not, however, state when NOT to use it or name an alternative sibling for reference-style questions.

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