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

Annotations already mark the tool read-only and idempotent, and the description reinforces this with 'Needs no sign-in and changes nothing.' It adds significant behavioral detail: exact pricing for photos and most video presets, the length-dependent 1-or-2 credit range for YouTube, the exact return object shape, and error behavior for invalid presets or out-of-range photo counts.

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?

The description is dense but well-structured: purpose first, then usage timing, then pricing rules, return shape, and error behavior. Every sentence contributes distinct information, and there is no repetition of schema fields.

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?

With no output schema, the description fully covers the return value, including minimum_credits, maximum_credits, final_price_known, charge_now: 0, and why. It also covers prerequisites, side effects, authentication needs, and error cases, making the tool fully callable without additional investigation.

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?

Although schema coverage is 100%, the description adds real meaning beyond the schema: it explains which output presets cost exactly 1 credit and why YouTube may cost 1 or 2. It also clarifies that photo_count failures produce errors naming valid values, giving the agent useful expectations for that parameter.

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 description uses a specific verb ('Price') and resource ('an Odile Formats job in credits'), and immediately distinguishes the tool from the follow-up unlock_job by saying it runs 'before anything is uploaded or charged.' This makes its role unambiguous even among many sibling tools.

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?

It states exactly when to use it: 'to tell the customer the cost and get their approval before unlock_job.' It also names get_catalog as the source of valid preset values, giving the agent an explicit alternative for validation. This is strong usage routing.

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