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

Annotations declare readOnlyHint=false and idempotentHint=false but don't explain why; the description supplies the missing rationale by disclosing the OPN account requirement, a 4-credit cost, and automatic refund on failure. That is real behavioral value beyond the structured fields, though it says nothing about run duration, rate limits, or partial-failure fee handling.

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?

Two sentences, no filler, and the output summary is front-loaded before the account/credit caveats. 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?

There is no output schema, but the description enumerates the three return artifacts (fee band per format, total liability by market, reformulation priority list), and covers auth, cost, and refund behavior. Nothing essential for a correct call 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?

Single parameter with 100% schema description coverage, so the baseline is 3. The description echoes the schema's framing ("packaging portfolio as text: formats, materials, unit weights, annual volumes and markets") without adding format or syntax guidance such as an example payload.

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?

Specific verb ("Estimate") plus resource ("annual Extended Producer Responsibility fees") plus scoped domain (packaging portfolio across named schemes). No sibling in the list computes EPR fees, so it is trivially distinguished from check_quote, cost_packaging_spec, and packiq_recyclability.

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?

The description implies when the tool applies (you have a packaging portfolio and want scheme-level fee liability), but it names no alternative and gives no exclusions — e.g. it doesn't say when to reach for packiq_quote_analysis or cost_packaging_spec instead. Usage is inferable rather than stated.

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