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

With no annotations provided, the description carries the safety profile itself: 'Read-only; never exposes secrets or signing material.' That substitutes for readOnlyHint and adds a meaningful privacy boundary. It still omits auth/permission requirements, behavior for an unknown txId, and retention of the evidence, so it is strong but not complete.

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, front-loaded with the purpose and contents followed by the safety note. No filler, no restatement of the tool name or schema, and every clause earns its place.

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, so the description must convey returns, and it does list the constituent parts of the evidence (provenance, delegation tree, approval state). That covers the essentials for a read-only lookup; only failure/empty-result behavior is unaddressed.

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?

There is a single parameter with 100% schema description coverage, and the schema already explains that txId is the value returned by authorize_payment. The description adds no format, constraints, or error semantics beyond that, so the baseline 3 is 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?

The description states a specific verb and resource ('Get the fuller evidence trail behind a previously-decided payment') and enumerates what the trail contains: policy/delegation provenance, delegation tree, approval state. It is clearly a read of post-decision audit data, but it never names or contrasts itself with the sibling x402shield_get_authorization, so an agent must infer the difference.

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 phrase 'behind a previously-decided payment' implies a prerequisite (a decision already exists) and the schema notes txId comes from x402shield_authorize_payment, so usage is implied. However, there is no explicit when-to-use-this-vs-get_authorization guidance and no stated condition or exclusion.

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