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

Annotations only say readOnly=false, idempotent=false, destructive=false; the description adds that credits are consumed exactly once, that a whole score is never charged again, and that downloads follow the account. Those are real behavioral facts beyond the annotations, though failure modes (insufficient credits, wrong price) are not described.

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?

Short and front-loaded: the action and price condition come first, then the consent gate, then the never-charge and no-purchase rules. Phrasing is slightly dense ('for exactly its price in existing credits, once') but every sentence carries a rule.

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 non-idempotent credit spend with no output schema, the description covers the consent gate, the once-only guarantee, and download behavior. It leaves out what happens when credits are insufficient or the score_id is invalid, which keeps it from a 5.

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 67% and consent/credits already have descriptions in the schema; the description mainly reinforces 'exact price a score tool reported' and 'consent=true'. score_id gets no semantics anywhere, so the description does not compensate 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?

The first sentence gives a specific verb and resource ('Open the whole of a previewed score') plus the transaction basis ('for exactly its price in existing credits'). It implies the distinction from open_score/apply_score_preview via 'previewed score', but never names the sibling it replaces, so sibling differentiation is inferred rather than explicit.

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?

States an explicit precondition ('Only after the user agreed to that exact number in this conversation') and a constraint ('once', 'Never offer purchases'). It doesn't enumerate alternatives such as open_score or discard_score_preview, so an agent must infer the routing from 'previewed score'.

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