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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the safety profile is covered. The description adds genuine non-derivable behavior: values are deep-merged by default and only replaced when replace_values=true, plus a secrets handling rule (ANKRA_SECRET_PARAMETER). This is real value beyond the annotations, though auth requirements and side effects on dependents are 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 tightly packed sentences, front-loaded with verb and resource, followed by the enumerated fields and the merge/secrets semantics. Every clause carries information and there is no filler.

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 7-parameter mutation with full schema coverage and no output schema, the description covers what can be changed, the default merge behavior, and secrets handling. It does not explain draft_id's page-context defaulting, but that is fully documented in the schema, so the remaining gap is minor.

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 the baseline is 3; the field listing (Helm values, chart_version, namespace, parents) largely echoes the schema. The description nevertheless adds one rule not present anywhere in the schema – use ANKRA_SECRET_PARAMETER for sensitive values – which lifts it above baseline.

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 states a specific verb (update) and a precise resource (an addon inside a stack profile builder draft), then enumerates the updatable facets: Helm values, chart_version, namespace, and parents. This clearly separates it from the add_/remove_addon_from_stack_profile_draft siblings without opening 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?

Usage is implied by 'update an addon inside a stack profile builder draft' – the agent can infer this targets an existing addon rather than creating one. However, there is no explicit when-to-use vs when-not, and no routing to alternatives such as add_addon_to_stack_profile_draft or remove_addon_from_stack_profile_draft.

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