OPA health check

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

Annotations already cover the safe-read profile (readOnlyHint, idempotentHint, non-destructive), so the description's job was to add behavioral depth beyond that, and it delivers: the exact endpoint, 200-vs-otherwise result semantics, the key gotcha that an unactivated bundle yields { healthy: false } rather than a tool error, and the OPA_UNREACHABLE failure mode. These are precisely the interpretation cues an agent needs and cannot derive from annotations or the schema.

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, roughly 70 words, with no filler. The endpoint is front-loaded, followed by result interpretation, the unreachable edge case, and finally the flags — a logical order where every sentence earns its place. Nothing is redundant with the schema or annotations.

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 zero-required-param, read-only health check with no output schema, the description is fully sufficient: it names the endpoint, defines both success and failure result shapes, covers the edge cases (unactivated bundle, unreachable server), and documents both optional flags. There is nothing an agent needs in order to call this tool correctly that is missing.

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% — both bundles and plugins already carry adequate descriptions. The description's phrase 'query flags to require those subsystems to also be healthy' adds a small amount of meaning by tying the booleans to the subsystem-health concept, which aligns with and slightly reinforces the schema. Since the schema does the heavy lifting, the baseline 3 is appropriate.

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?

Names the specific resource (`/health` endpoint) with a clear verb ('Hit'), and then defines the expected response semantics. This makes the tool immediately distinguishable from the many siblings in the namespace, especially opa_status and opa_config, without needing to open their schemas.

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 conveys useful context about when to use the tool — checking whether the OPA server (and optionally its subsystems) is healthy — and clarifies that an unactivated bundle appears as a health result rather than a tool error, which affects result interpretation. However, it never explicitly names alternatives or gives when-to-use / when-not-to-use conditions, so routing among overlapping siblings like opa_status and opa_config is left to inference.

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