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

Annotations already provide readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, so the baseline safety profile is covered. The description adds meaningful behavioral context beyond these: the tool is paid ($0.002 per call), deterministic, and explicitly a 'technical interoperability signal only' with no downstream execution guarantee. This helps agents decide whether to spend the call.

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?

Four sentences, each adding distinct value: purpose, comparison dimensions, technical-scope caveat, and pricing. The most important facts are front-loaded and there is zero fluff or repetition.

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 one-parameter tool with no output schema, the description covers the tool's purpose, cost, determinism, and limits, which is good. However, it omits any detail about what the returned matrix looks like, how the surfaces parameter should be shaped, or what happens on invalid input. These gaps matter because there is no output schema to fall back on.

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?

With 0% schema description coverage, the description must carry the parameter meaning. It mentions 'across agent-commerce surfaces' and what the tool compares, implying each surface has declared protocols, capabilities, rails, and fields, but it never defines what a 'surface' actually is (URL? object? ID?) or the expected structure of the array items. This is too vague for an agent to construct a correct request without further guessing.

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 ('compares') and resource ('compatibility matrix across agent-commerce surfaces'), and enumerates the exact dimensions compared: protocols, capabilities, authentication/payment rails, and input/output fields. This distinguishes it from siblings like assurance_interop or schema_transform_plan, which would address only a subset of these dimensions.

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 implies a use case: assessing technical interoperability across agent-commerce surfaces, and the caveat 'does not guarantee downstream execution' hints it is not for execution safety. However, it never names an alternative tool or gives explicit when-to-use/when-not-to-use guidance, so the agent is left to infer routing from the tool's name and context.

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