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

Annotations only say the tool is non-read-only, open-world, non-idempotent and non-destructive; the description goes well beyond that by disclosing the dual billing model (site credits ~42 per image at default vs. a separate USD wallet for API keys) and the quote-then-confirm cost-approval protocol. That is exactly the non-obvious behavioral context an agent needs before spending user money.

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 compact sentences with the purpose front-loaded, then cost model, then the approval protocol. Dense but every sentence carries decision-relevant information; no filler or repetition 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?

With no output schema, the description compensates by stating the output is transparent PNG layers. It covers cost and approval flow fully. It does not mention that generation is asynchronous or that results are retrieved via get_job, which is a small but real gap given the sibling set.

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 per-parameter descriptions already carry most semantics and the baseline is 3. The description adds value by linking parameters into a workflow: which approval field pairs with which auth type (max_credits for OAuth, currency=USD plus decimal max_usd for API keys), which is a cross-parameter relationship not obvious from any single field.

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?

Opens with a specific verb and resource: 'Separate a finished picture into editable layers (text, people, objects, background) as transparent PNGs.' The enumerated output layer types make it clearly distinct from nearby siblings like remove_background or erase_object, which produce a single modified image rather than a multi-layer breakdown.

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?

Gives concrete procedural guidance: omit approval to obtain a quote, then confirm max_credits (OAuth) or currency=USD with max_usd (API keys). It does not explicitly state when to prefer this over remove_background, so the alternative-selection guidance is implied by the layer breakdown rather than spelled out.

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