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

With no annotations, the description carries the burden and does well: it discloses the verdict levels (pass/warn/fail/unknown), the effect of incomplete schain.complete, the app_bundle origin behavior ('not_evaluated'), and the components of the return object. It omits explicit side-effect disclosure (e.g., the optional buyer recording is only in schema) and network dependencies, but overall it is transparent.

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 compact yet information-dense: it opens with a clear context, uses bullet points for the four checks, and ends with the return summary. Each sentence adds value without waste, appropriate for a tool of this complexity.

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?

Despite having no output schema, the description states the return types (per-node array, aggregate verdict, recommendations, sigil_token) and key edge cases (app_bundle ads.txt, schain.complete). It could provide more detail on the per-node result structure or failure modes, but the essential information is present.

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 coverage is only 25%, but the description compensates by explaining the meaning and source of schain, site_domain, and app_bundle, as well as the mapping from OpenRTB fields. It also clarifies schain.complete semantics. The buyer parameter is already documented in the schema, so the distribution is balanced.

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 specifies the tool's function with a concrete verb ('verifies') and a unique resource ('SupplyChain object from an OpenRTB bid request'), and enumerates four specific checks (origin ads.txt, per node, owner-domain, schain.complete). This clearly distinguishes it from sibling sigil_verify_* tools.

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 'bid-time contract' establishes the intended context (verification during bid processing), and the description explains required inputs (schain, site_domain or app_bundle) and provides OpenRTB field mapping. It does not explicitly name alternatives or exclusion criteria, but the context is sufficiently clear.

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