Param Discovery

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

Beyond the annotations (readOnlyHint:false, openWorldHint:true, destructiveHint:false), the description adds crucial behavioral context: it flags the tool as 'AGGRESSIVE — requires human approval' and states 'Guessing costs requests.' This informs the agent of the tool's active, high-cost nature, which is not captured in the annotations alone.

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 long and front-loaded with the most critical information (the aggressive nature and approval requirement). Every sentence earns its place, providing purpose and usage guidance without unnecessary verbosity.

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 (a live scanning tool with an output schema), the description covers the essential aspects: purpose, usage prerequisite, and behavioral warnings. The missing parameter explanations are a minor gap, especially since the output schema likely clarifies return values. Overall, the description is well-rounded and sufficient for an agent to invoke it correctly.

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 0%, so the description must compensate for the undocumented parameters. It implicitly identifies 'target' as the URL ('Discover hidden request parameters on a URL'), but it does not explain the 'method' parameter (e.g., GET/POST) or provide any format hints. The description adds minimal value beyond what a user could guess from the schema.

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: 'Discover hidden request parameters on a URL with Arjun.' This includes a specific verb (discover), a resource (hidden request parameters on a URL), and the tool used (Arjun). It effectively distinguishes itself from siblings like content_discovery and endpoint_discovery, which have different objectives.

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 usage guidance: it instructs the agent to 'Mine endpoint_discovery's archive results for parameter names first' and notes that guessing costs requests. This tells the agent when to use this tool (after exhausting free, known parameter names) and directly names the alternative (endpoint_discovery). The warning about aggressiveness and human approval further sets expectations.

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