Service Directory

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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering safety and open-world behavior. The description adds value by revealing that the tool is interactive ('Opens an interactive directory') and that it internally calls l402-search, which implies a wrapper behavior and potential user-interface side effects. This is beyond the annotations and is not contradictory.

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 sentences with zero waste. The primary purpose is front-loaded ('Browse and search paid API services'), and the additional details about the interactive directory and internal call are placed efficiently. Every sentence earns its place.

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 has no parameters and annotations already convey read-only and open-world behavior, the description provides sufficient context to understand what the tool does. However, it does not describe the return format or what 'interactive' means precisely, and it does not differentiate from similar siblings. These gaps are minor for a zero-parameter tool, so a 4 is appropriate.

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 tool has zero parameters, so there is nothing to document. Per the instructions, a zero-parameter tool gets a baseline of 4 since the schema coverage is trivially 100% and no description compensation is needed. The description does not need to add parameter meaning.

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 states a clear verb and resource: 'Browse and search paid API services.' It adds context by mentioning it opens an interactive directory of L402/x402 services discovered on Nostr and that it calls l402-search internally. However, it does not explicitly differentiate itself from siblings like l402-search or l402-discover, which could be confused as alternatives, so it stops short of a 5.

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 usage context by saying it opens an interactive directory and calls l402-search internally, suggesting it is a higher-level wrapper for interactive browsing. But it provides no explicit 'when to use' vs 'when not to use' guidance, nor does it name any sibling tools as alternatives. The usage conditions are left to inference.

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