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

The description directly contradicts the annotations. Annotations include openWorldHint: true, implying the tool may access external data or open-world knowledge, but the description explicitly states it 'does not discover, fetch, verify, or enrich evidence' and is bounded to the buyer-supplied facts. This is a serious inconsistency, warranting a score of 1.

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 a single, efficient sentence that front-loads the core purpose, followed by a clarifying exclusion and cost/payment info. Every word adds value, with no redundancy or filler. It is concise yet informative.

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 tool with 4 fully documented required parameters and no output schema, the description provides sufficient context: it clarifies the input boundary, the transformation nature, and the cost. It leaves no major gaps about usage or input constraints. However, the contradiction with openWorldHint slightly undermines trust, so a 4 rather than 5.

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%, with detailed descriptions for each parameter (e.g., 'Explicit UTC timestamp with a real Gregorian calendar date' for snapshotAt, and 'Input order is ignored; rows are sorted deterministically' for rows). The tool description adds no additional parameter semantics beyond what the schema already provides, so a baseline of 3 is appropriate.

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 states the tool's function: 'Turn a buyer-supplied snapshot of US brand signals into one bounded deterministic machine-readable brief.' It uses a specific verb ('Turn') and resource ('buyer-supplied snapshot of US brand signals'), and explicitly distinguishes itself from sibling tools by noting it 'reduces the facts you provide and does not discover, fetch, verify, or enrich evidence.' This makes its purpose unambiguous and distinct.

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 provides clear context on when to use the tool: when the user already has a snapshot and wants a composed brief. It also gives exclusions—'does not discover, fetch, verify, or enrich evidence'—which tells the agent not to use this tool for evidence gathering or enrichment. However, it does not name specific alternative tools, so it stops short of explicit 'use X instead' guidance.

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