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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real value beyond that: it discloses the return envelope (JSON:API { data }), warns the payload contains PII, and maps to the underlying REST verb/path. It does not describe not-found/error behavior, which keeps it short of a 5.

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 tight sentences with zero filler: identity and scope first, then return shape, PII warning, and REST mapping. 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?

With no output schema, the description usefully covers the return format and PII content, and the single required param is schema-documented. Only the error/not-found path is unaddressed, a minor gap for a simple read-by-id tool.

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% and the single parameter already documents the 'txn_...' format, so the schema carries the load. The description adds no syntax or constraint detail beyond what the schema provides, making 3 the correct baseline.

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 (get), resource (transaction), and scope (single, by id), then clarifies what a transaction record is ('submitted for transaction fraud/monitoring analysis'). The word 'single' implicitly differentiates it from the sibling persona_list_transactions, but it never names that alternative explicitly.

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 is only implied by 'by id' — the agent can infer this is the retrieval-by-identifier path versus the list tool, but no when-to-use, when-not-to-use, or alternative is stated. Adequate minimum, not explicit guidance.

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