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

No annotations are provided, so the description carries the full burden. It indicates this is a read-only listing operation and discloses the PostHog connection prerequisite. However, it does not describe the return format, pagination behavior, or potential errors, leaving some behavioral aspects unstated.

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?

Two sentences with zero redundancy. The first sentence states purpose and defines the resource; the second provides usage direction and a prerequisite. Information is front-loaded and every word 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?

For a straightforward list operation with five documented parameters, the description covers purpose, usage, and a prerequisite. It does not mention return structure or ordering, but that is implied and likely consistent with other list tools. A minor gap, but overall sufficient for correct invocation.

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?

All five parameters are fully described in the input schema (100% coverage). The description does not add extra meaning to the parameters beyond what the schema already provides, so it meets the baseline of 3 for high schema coverage.

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 a specific verb ('List') and resource ('Replay Vision scanners'), and defines what those are ('AI probes that watch session recordings'). This distinguishes it from sibling tools like posthog_get_vision_scanner (single) and create/update/delete, which are obviously different operations.

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 explicitly says when to use it: 'Use when checking which scanners exist before creating or updating one.' It also notes a prerequisite: 'Only works if PostHog is connected.' It does not explicitly name alternative tools, but the context implies the create/update tools are the alternatives, so guidance is clear enough.

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