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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=false, so the description is not the sole carrier. It still adds real behavior: partial updates leave unsent fields untouched, the score is stored verbatim and never computed server-side, and specific failure conditions are named. The one gap is that destructiveHint is never addressed — overwriting an existing title or video type is not called out as irreversible.

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 tight sentences, front-loaded with the action and scope, then the update semantics, then failure modes. No filler, no restatement of the title.

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?

Covers scope, partial-update contract, score storage rules and error conditions for a 5-parameter mutation whose schema is fully documented and whose annotations carry the safety profile. The residual gap is the return value: with no output schema, the description says nothing about what a successful call yields (e.g. whether the updated script is echoed back).

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?

With 100% schema coverage the baseline is 3, but the description adds cross-parameter semantics the per-field descriptions cannot: omission means "leave alone" for every optional field, not just viral_score. The out-of-ten score rule is reiterated from the schema, so some overlap, but the partial-payload contract is genuinely new.

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 ("Update a script") plus a scope qualifier (scripts the signed-in user can edit), which is enough to separate it from get-script/list-scripts/create-script. It doesn't explicitly name any sibling, so sibling differentiation is implied by the resource rather than stated.

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?

"Only what you send is changed" communicates partial-update intent, and the error conditions (missing script, no edit permission) tell the agent when the call fails. But there is no explicit when-to-use guidance, no mention of alternatives such as update-thumbnail-brief or update-storyboard, and the dependency on obtaining `id` only appears indirectly in the schema.

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