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

Beyond the annotations (readOnly=false, openWorld=true, idempotent=true, destructive=false), the description discloses that the tool sends a network request and consumes receipt quota, which are important side effects. It also clarifies the evidential scope (proves what was served and when, not truth), adding behavioral nuance not captured by annotations.

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 serving a distinct purpose: main action, receipt characteristics, scope clarification, and network/quota side effect. No filler or redundancy, and the most important information is front-loaded.

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?

Given the availability of sibling tools and the absence of an output schema, the description sufficiently covers what the tool does, its side effects, and its output nature (signed receipt). It could mention prerequisites like authentication or rate limits, but the quota mention partially covers this. Overall, it's complete enough for an agent to select and invoke the tool correctly.

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 schema covers all 4 parameters with descriptions, so the baseline is 3. The tool description does not add parameter-specific details beyond the schema, but it does set the context that the capture is for a 'web source served' which aligns with the 'url' parameter. No additional semantic value is provided.

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 action ('Freeze proof of what a web source actually served') with a specific resource and context. It distinguishes itself from siblings by emphasizing the signed receipt and offline verification, making its role in the evidence-capture workflow unambiguous.

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 'before quoting or acting on it' provides clear context for when to use capture. However, it does not explicitly name alternatives or exclusion criteria compared to sibling tools like verify or get_receipt, so it stops short of full guidance.

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