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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral context: it is 'free live', requires 'no account', and does not create a 'persistent monitor'. It does not explicitly mention potential limitations or return details, but the core behavior is well disclosed beyond the 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?

The description is three sentences long, with the main purpose front-loaded in the first sentence. Every sentence earns its place: the first states what it does, the second when to use it, and the third how to transition to an alternative. No filler words.

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?

The description provides complete workflow context: why to use this tool (proves what would be monitored), when to use it (before checkout), and what to do after (offer create_monitor only when needed). An output schema exists, so return values don't need explanation. The sibling context is sufficiently addressed by the explicit comparison to create_monitor.

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 including enums and usage notes (e.g., pricing_page, vendor_claim). The tool description itself doesn't add parameter-level meaning, which is acceptable since the schema already fully documents them.

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 with a specific verb ('Capture') and resource ('free live baseline for a source'). It distinguishes itself from 'create_monitor' by explicitly noting it works 'without creating an account or persistent monitor', and its placement before checkout is made clear.

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 gives explicit when-to-use guidance: 'Call this before recommending checkout'. It also states the alternative: 'offer create_monitor only when the user wants scheduled checks, history, or change alerts', which advises when not to use create_monitor and implies preview is for initial validation.

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