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

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=true. The description adds valuable context beyond annotations: optimistic-concurrency behavior (version 409 on stale reads) and the clobbering risk. However, it doesn't mention what field-level guarantees exist (e.g., partial vs full update) or the auth requirement ('your charm' implies ownership only).

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 compact sentences, the first stating scope and the second front-loading the critical race-condition guidance. 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 12-param mutation tool with 50% schema coverage and no output schema, the description should do more: clarify partial update semantics, ownership/auth requirements, and what a successful update returns. It covers the most important behavioral hazard (version conflicts) but leaves several agent-relevant gaps.

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 50%, so half the parameters (tags, emoji, title, tagline, agent_notes, description) lack schema-side documentation. The description covers slug and version semantics, but doesn't explain what the undocumented fields do or the enum meanings for data_policy. It only partially compensates for the coverage gap.

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 specific verb (Change) and resource (any field of a charm you published). Distinguishes itself from sibling publish_app (create) and rollback_app_data, and names get_app as the source of the version parameter.

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 a clear procedural precondition: pass version from get_app to avoid clobbering a newer edit. No explicit when-not-to-use or named alternatives (e.g., delete_app, publish_app) are mentioned, so it falls short of a full 5.

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