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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description goes further by disclosing that the response is cryptographically signed, that the payload contains per-signal quality/confidence data, and that the JWS is detached and meant for offline verification — meaningful context beyond the annotations.

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 sentences with no filler: the first front-loads what is returned, the second front-loads the verification directive. The second sentence is dense but each named field earns its place by driving an actual verification step.

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 the description need not enumerate return values, and it still surfaces the security-critical fields an agent needs. For a zero-parameter read tool the coverage is strong; the only gap is the absence of any routing hint against the sibling get_trust_receipt.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; per the rubric, a 0-parameter tool has a baseline of 4. The description's remaining naming (jwks_snapshot_uri, jws_compact, signing_kid, payload_hash_sha256) belongs to the output shape, not inputs.

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 ('Get Demo Store's signed trust score'), and adds version (v4.1), scale (0-100), and the contents of the payload (per-signal data quality, confidence level, detached JWS). However, it never distinguishes itself from the close sibling get_trust_receipt, so an agent must infer which trust-related tool to call.

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 description gives a clear verification workflow ('download the JWKS..., validate jws_compact..., recompute payload_hash_sha256'), which is useful procedural guidance. It does not, however, state when to call this versus get_trust_receipt or get_merchant_profile, leaving usage selection to inference.

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