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

With no annotations, the description carries full burden. It discloses that the tool is paid ($0.01 per call) and outlines the x402 payment scheme, including that a first call without payment_signature returns payment requirements. It also notes the return of watchId and checkEndpoint URL.

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 two short sentences plus a payment note. It is efficient, front-loaded with purpose, and every sentence adds value.

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 no output schema, the description explains the return value (watchId and checkEndpoint) and the payment flow. It covers the main aspects but lacks details on condition evaluation or endpoint kind behavior. Reasonably complete for the complexity.

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?

All 6 parameters are described in the input schema (100% coverage). The description adds no extra meaning beyond the schema, so baseline 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 registers a watch for real-time monitoring, listing specific data types (prices, gas, weather, etc.). This distinguishes it from sibling tools like get_crypto_prices (one-time query) or check_watch (checking watch status).

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 use for continuous monitoring, but does not explicitly state when not to use it (e.g., for one-time queries) or mention alternatives. It does explain the payment process, guiding agents on the two-step call flow.

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