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

With no annotations, the description carries the full burden and largely meets it: it declares read-only semantics, discloses the env-var prerequisites, states the tenant is resolved from configuration and never from an argument, and enumerates the OK/REFUSED/UNAVAILABLE statuses including that failure degrades to UNAVAILABLE rather than invented data. It also warns that a version of the API not serving this view yields UNAVAILABLE. The main omission is auth/permission specifics and rate or latency behavior.

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 read-only and no-side-effects statement is front-loaded, followed by prerequisites and then return statuses, which is a sensible ordering. Some phrasing is choppy and slightly redundant ('it writes, signs and executes nothing' overlapping with 'Read-only view'), but nearly every sentence carries a real constraint.

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?

Because an output schema exists, the description is not obliged to explain return values, though doing so is helpful here. The unresolved gap is the free-form request object with zero schema documentation, and the absent sibling routing, which together leave meaningful ambiguity for an agent deciding how to call this versus the evidence and verification siblings.

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 coverage is 0% and the single parameter is a free-form nested object with additionalProperties true, so the description must define its shape — and it does not. It adds one genuinely useful constraint (the tenant comes from a setting, never an argument) and says the receipt is 'supplied', but never indicates whether the request carries a receipt id, a full receipt body, or scoping fields.

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 opening sentence names a specific resource and view type: an evidence view of a single supplied receipt, showing what could and could not be checked. That is clearly distinct from a mutating tool, but the description never contrasts it with close siblings such as verify_receipt, get_decision_evidence or get_intervention_evidence, so an agent must infer the boundary from the name alone.

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?

Usage context is implied rather than stated: read-only, no writing/signing/executing, requires three TRUST_GATE_* settings, and returns UNAVAILABLE when a surface is off. There is no explicit 'use this when... instead use X when...' routing, and the framing 'a mapping or readout is not a compliance finding' hints at scope limits without telling the agent when to prefer a different tool.

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