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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds only the availability precondition; it does not explain the reliance on a retailer program, what happens if the program has not returned, or any failure modes.

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 short sentences with no filler, and the precondition is stated plainly. The opening metaphor ('Read the till') costs a little clarity for the sake of brevity, but the text is appropriately sized for a one-parameter read tool.

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 return values need not be described, and the single parameter is the only structural gap. Still, a thin one-parameter tool with a prerequisite should make the dependency on the handoff flow and the jargon 'till' unambiguous, which it only partially does.

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 0% for the single required parameter handoff_id, so the schema contributes nothing. The description's reference to a 'campaign id for a handoff' only loosely implies where handoff_id comes from, without stating that handoff_id is the id issued by the prior handoff and how to obtain it.

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 retrieval verb ('Read') and a resource ('results of a campaign'), but the framing 'Read the till' is idiosyncratic jargon that is not explained, and it never distinguishes this tool from siblings like a2a_handoff or gate_transaction. An agent gets the gist (fetch campaign measurement results) but not a precise contract.

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?

It supplies one explicit precondition — available only after the program returns a campaign id for a handoff — which is genuinely useful sequencing information. However, no alternatives are named and there is no when-not-to-use guidance, so the agent still has to infer when this tool is preferred over a2a_handoff or check_eligibility.

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