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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the description only needs to add value beyond that. It does so by disclosing what the output contains: national totals and averages, all years, and categorization by payment-nature type. This gives the agent a concrete expectation of the result.

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 description is two short sentences with no filler. It front-loads the most important qualifier ('National-level') and immediately specifies the core value and breakdown. Every word contributes useful information.

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?

For a zero-parameter, read-only summary tool, the description is complete: it states the level of aggregation, the time coverage, the metric types (totals and averages), and the dimension (payment-nature category). No output schema exists, but the description sufficiently sets expectations for what the tool returns.

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 has zero parameters and the schema is empty, so there are no parameter details to explain. Per the baseline for zero-parameter tools, this is handled well; the description focuses on the data scope instead of unnecessary parameter commentary.

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 clearly identifies the resource (Open Payments national totals and averages), the scope (national-level, across all years), and the breakdown (by payment-nature category). It distinguishes itself from sibling tools like open_payments_by_company and open_payments_state_totals by its explicit national focus.

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 clearly establishes the context for use: a national-level overview of Open Payments data across all years. It does not explicitly name alternatives or state when not to use it, but the scope is clear enough for an agent to select it over more granular open_payments siblings.

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