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

Annotations already declare non-read-only, non-idempotent, non-destructive, and the description adds real behavioral context beyond them: the registry is indexed after the call and charts become usable for stack design. However, it says nothing about authentication needs for private/OCI registries, duplicate-name behavior, or how long indexing takes — gaps that matter for a mutation tool.

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, each doing distinct work: purpose, post-call consequence, usage trigger. It is front-loaded with the action and free of filler, though the long inline example quote is slightly heavier than needed.

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 3-parameter mutation tool with no output schema and adequate annotations, the description covers what it does, why it matters, and when to invoke it. It could be more complete about credential requirements and indexing side effects, but nothing essential to calling it correctly 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 coverage is 100%, so all three parameters (including the http/oci enum and default) are already documented in the schema. The description's URL example duplicates the schema's own example and adds no new semantics, so 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?

Specific verb+resource: 'Add a Helm chart registry to the organisation's catalog,' which is unambiguous and distinct from siblings like list_helm_registries or sync_helm_registry. It stops short of naming a sibling explicitly, but the 'isn't in the catalog yet' framing implicitly separates it from listing/lookup tools.

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 an explicit when-to-use trigger ('when the user needs charts from a registry that isn't in the catalog yet') with a concrete example utterance. It does not state when not to use it (e.g., registry already present, or an OCI registry that needs credentials first), so it falls short of full alternative routing.

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