x402_estimate

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

With no annotations provided, the description carries the full burden. It discloses the key safety trait that no actual payment is made ('without actually paying'), which is essential for a tool that could otherwise be mistaken for a payment operation. Still, it does not mention other potential behaviors like network access or approximation guarantees.

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 extremely concise: two short sentences that front-load the primary action and purpose. Every word earns its place, with no redundant information.

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 a single parameter and no output schema, the description gives a reasonable overview but lacks information about the return value (what the estimate looks like) and does not differentiate from similarly named x402_estimate_cost. The 'Useful to check costs' context is helpful but overall leaves some gaps for full autonomous use.

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 100% with the single parameter 'url' described as 'The URL to check'. The description adds only that the URL is the target for potential payment, which is a slight extension but not substantial additional meaning. It does not clarify format, required scheme, or any URL-specific constraints beyond the schema's 'uri' format.

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 action (estimate) and the object (payment required for a URL). It also distinguishes itself from payment-executing tools by explicitly saying 'without actually paying', which separates it from sibling tools like x402_pay_request or x402_send.

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 a useful context ('Useful to check costs before making a request') that implies when to use the tool. However, it does not explicitly mention alternatives or when not to use it, leaving ambiguity with similarly named siblings like x402_estimate_cost and x402_yield_estimate.

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