nvr_purge_exports

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

With no annotations, the description carries the full burden and does well: it discloses the double-gate requirement, the environment flag needed, the default retention window, and the dry-run preview path. It does not state whether purged exports are recoverable or what happens if the retention env var is unset beyond the default, leaving a small gap for a destructive operation.

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 tight sentences with no filler, front-loading the action and retention rule before the gating and preview details. 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?

An output schema exists, so return values need not be explained, and the description covers scope, gating, and dry-run preview adequately for a destructive retention purge. Minor omission: it never confirms irreversibility or whether the retention-days variable can be overridden per call.

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 coverage is 100% and the single parameter's meaning (confirm_write must be literal boolean true) is fully documented in the schema. The description only echoes the gating semantics via the env flag, adding marginal value over the structured field — baseline 3 applies.

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?

States a precise verb+resource+predicate: delete exports older than a retention window (default 7 days). The retention-scoped bulk nature clearly separates it from the sibling nvr_delete_export, which acts on a single export, without needing to read either schema.

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?

Gives concrete prerequisites for invocation (VIGI_NVR_ALLOW_WRITES=true plus confirm_write=true) and points at a safe alternative mode (VIGI_NVR_DRY_RUN=true) to preview the operation. It stops short of explicitly telling the agent when to prefer this over nvr_delete_export, so it is strong context rather than explicit routing.

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