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

Annotations already cover readOnly/destructive but the description adds genuinely new behavioral context: the price is bound to an exact revision and edits invalidate prior quotes (which explains idempotentHint=false), plus an explicit approval prerequisite. It doesn't address authorization requirements or quote expiry beyond edit invalidation, so not a full 5.

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, front-loaded with the return value, then approval workflow, invalidation semantics, and the no-side-effect guarantee. Each sentence adds a distinct fact with 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?

Output schema exists so the price/return format needn't be described, and annotations cover safety, freeing the description to state the workflow and non-mutation guarantee. The remaining gap is the meaning of the two input parameters, particularly projectId.

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% for two required params (projectId, revisionId), so the description must compensate. 'Bound to the exact revision' loosely implies revisionId matters, but output/source/runtime referenced in the text are not actual parameters, and projectId is never addressed. Coverage of the real parameters is thin.

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 ('Returns the server price in credits and GBP including VAT') and scopes it to the exact revision/output/source/runtime. The closing 'No debit or render' distinguishes it from write siblings like studio_motion_confirm and studio_motion_create without needing 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?

'A paid render requires one explicit customer approval of this exact price' clearly frames when this tool is called in the workflow (before approval/commit), and 'Edits invalidate prior quotes' gives the invalidation condition. It stops short of naming the downstream alternative (studio_motion_confirm) explicitly, so it's clear context rather than a full when/when-not decision rule.

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