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 discloses that 'Text is untrusted' (a security caution) and that it returns structured result and reasoning. However, it does not explicitly state whether the operation is read-only, nor does it describe potential errors or side effects. For a get operation, the lack of an explicit read-only hint is a minor 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?

Three sentences with no filler. The core purpose is front-loaded, followed by usage guidance, a security note, and a prerequisite. Every sentence earns its place and no redundant information is present.

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 simple get-by-ID tool, the description covers the essential aspects: what it returns, when to use it, a security caveat, and a dependency. The optional scanner_id is clearly documented in the schema, and the output format is hinted (structured result + reasoning). The only minor omission is an explicit statement that it's a read-only operation, but the overall context is sufficient for an agent to call 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 100%, so all parameters are documented in the schema (id, companyId, scanner_id). The description adds minimal extra meaning—it only reiterates 'single scanner finding' without elaborating on the parameters or their optionality. Baseline 3 is appropriate when the schema already carries the parameter documentation.

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 starts with a clear verb and resource: 'Get one Replay Vision observation', specifying it returns 'structured result + model reasoning'. It distinguishes from the sibling list tool by emphasizing 'one' and 'single scanner finding', so an agent can clearly tell it apart from posthog_list_vision_observations.

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?

Explicitly states when to use the tool: 'Use when reading a single scanner finding.' It also provides a prerequisite ('Only works if PostHog is connected'), and the 'single' wording implicitly contrasts with list operations, giving clear context without naming alternatives.

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