Riddle MCP Server

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

With no annotations, the description carries the full burden of behavioral disclosure. It states the tool returns base64 images, which is useful, but lacks critical details: it doesn't mention whether this is a read-only operation, potential rate limits, authentication needs, error handling, or how device selection affects output. For a tool that performs external actions (screenshotting URLs), this is a significant gap.

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 and front-loaded: two sentences that directly state the action and output with zero wasted words. Every sentence earns its place by conveying essential information efficiently.

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 (external actions, multiple parameters) and lack of annotations or output schema, the description is incomplete. It misses behavioral context like safety, performance implications, and error scenarios. While concise, it doesn't provide enough information for an agent to use the tool confidently without additional assumptions.

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 50% (only 'urls' has a description). The description adds no parameter semantics beyond what the schema provides—it doesn't explain the 'device' parameter's purpose or impact, nor does it clarify URL format requirements. With partial schema coverage, the description doesn't compensate adequately, but it doesn't contradict the schema either.

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: 'Screenshot multiple URLs' specifies the verb (screenshot) and resource (URLs), and 'Returns array of base64 images' indicates the output format. It distinguishes from siblings like 'riddle_screenshot' by emphasizing batch capability ('multiple URLs'), though it doesn't explicitly contrast with all siblings.

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?

No guidance is provided on when to use this tool versus alternatives. It doesn't mention when to prefer this batch tool over 'riddle_screenshot' (likely for single URLs) or 'riddle_click_and_screenshot' (which may involve interaction), nor does it specify prerequisites or exclusions for usage.

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