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

Annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=true, idempotentHint=true, openWorldHint=true), so the bar is lower. The description still adds real value: it scopes the mutation to metadata only, states the immutability constraint on image bytes, and discloses the 422 error on an unknown role.

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 short sentences, front-loaded with the operation and its scope; the constraint and the error behavior follow in descending order of importance. 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?

An output schema exists, so return values need no explanation. The description covers scope, identity, immutability, and error behavior; the only omission is whether omitted fields are left untouched (which the idempotentHint and optional params largely imply).

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 schema already documents id, name, role and context, so baseline 3 applies. The description adds only 'by UUID' and the 422-on-unknown-role behavior, which is marginal beyond the schema's enum for role.

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 (update), resource (asset), exact mutable surface (name and/or role), and the key identifier (UUID). It is clearly separable from create_asset, delete_asset, and list_assets without opening any 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?

Gives an explicit when-not and names the alternative for the common mistaken case: image bytes cannot be changed, so use create_asset instead. It does not spell out what 'role' is for or when a caller should clear it versus assign it, but the routing guidance is concrete.

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