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

Annotations already declare a non-idempotent, destructive write. The description adds value beyond them: it discloses what is preserved (interface, controller, other avatar links), that it does not publish, and that an optimistic-concurrency read is required first. It stops short of describing the failure mode when expectedVersionId is stale, but the mutation profile is well covered.

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?

Four short sentences, zero filler, with the action front-loaded and the concurrency guard and non-publishing constraint following immediately. 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?

For a 4-required-parameter mutation with no output schema and no parameter descriptions, the description covers the operation, the concurrency requirement, what is preserved, and what it explicitly does not do. The only gap is what the call returns, which matters slightly since no output schema exists.

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 0%, so the description must carry the burden; it explicitly names expectedVersionId and implicitly maps workspaceId, liveWorldId ('Worldstream draft'), and characterId ('existing workspace avatar'). It adds no format or constraint details (e.g., ID patterns), so it falls short of a full 5.

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 and resource ('Link an existing workspace avatar to a Worldstream draft'), which is distinct from siblings like create_live_avatar, update_live_avatar, and send_live_avatar_message. It does not, however, explicitly name a sibling or a disambiguation rule.

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 concrete prerequisite ('Read the world first and supply expectedVersionId') and a scope limit ('Does not publish'), which tells the agent when this is the right tool versus a publish step. No explicit alternative tool is named.

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