buy_capability

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

With no annotations, the description fully discloses behavioral traits: automatic detection of free vs paid, verification of payment recipient, timeout returning job event ID, and price confirmation if max_price_lamports is not set. No contradictions.

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 concise 3-4 sentences, front-loaded with the core purpose, and every sentence adds value without redundancy. It is well-structured and efficient.

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 tool's complexity and lack of output schema, the description covers key behaviors: free/paid handling, timeout, price confirmation. It mentions that on timeout a job event ID is returned, which is useful. It could clarify normal success return, but overall it is fairly complete.

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 0%, so the description compensates by adding meaning for key parameters: max_price_lamports as auto-approve limit, timeout_secs with default/max, and implies identifiers for provider_npub and capability. Input is less described but overall adds significant semantic value.

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 purpose: 'Buy a capability from an agent.' It differentiates from sibling tools like send_payment by focusing on buying capabilities with automatic detection of free vs paid, and mentions specific behaviors like verifying payment recipient and timeout handling.

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 explicit guidance on when to use the tool (to buy a capability) and explains key behaviors for free vs paid, auto-approving payments with max_price_lamports, and timeout handling. It lacks explicit exclusions or alternatives but is clear enough for an agent to decide.

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