Price a Usage change before applying it

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

With no annotations, the description carries the full burden and does well: it declares read-only semantics ('nothing is written') and explains the two result modes (current charge vs. recurring cost with next_term). It doesn't cover authorization requirements or rate limits, and the future-date restriction lives only in the schema.

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?

Dense but front-loaded, starting with the core purpose and read-only guarantee. The sentences are long and pack multiple clauses, but every clause carries information an agent needs.

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?

No output schema and no annotations, yet the description compensates by describing what is returned (current charge, and recurring cost when next_term is set) and the sequencing relative to the write tools. Minor gaps remain on the exact response shape but nothing critical is missing.

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 100%, so the baseline is 3, but the description adds a genuine cross-parameter constraint absent from the schema: 'Pass exactly one of increment, quantity_current or is_enabled, matching the Feature's type.' That mutual-exclusivity and type-matching rule is real added value.

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 ('Prices an intended Usage change without applying it') plus a secondary function ('checks that it is allowed'). It clearly separates itself from the push_* siblings by naming them as the write operations it precedes.

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?

Explicitly says when to call it ('before push_usage_increment, push_usage_quantity or push_usage_enabling whenever the change is billable') and prescribes the downstream workflow ('show the amount to the end customer for confirmation before the write'). It also gives a selection rule among the mutually exclusive parameters.

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