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

readOnlyHint=true already establishes safety, and the description adds meaningful behavior: default FBM-only scope, fbmOnly=false including FBA, missingOnly behavior, pagination via limit/offset, and the key semantic that currentCost null means the seller's rate book applies. It leaves minor operational details (ordering, auth) unstated but covers the important data behavior.

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?

Front-loads the resource definition, then the intended use, then defaults/filters/pagination. Every clause carries information about the result shape or call behavior, with no filler.

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, so the description appropriately explains the returned row composition (account, ASIN, SKU, isFbm, L24M sales, currentCost) and the null override meaning. It omits return ordering and pagination metadata, but is otherwise sufficient for an agent to call and interpret this read-only worksheet.

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 high (71%), so the baseline is 3, but the description adds meaning beyond the schema by clarifying that fbmOnly=false includes FBA and by explaining the null-currentCost interpretation. It does not extend the accounts or reason parameters, but it meaningfully supplements the filtering semantics.

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 the specific resource and shape: a per-delivery-zone FBM worksheet with one row per (account, ASIN, SKU) product, including channel, L24M sales, and current override. It distinguishes itself from the downstream import_fbm_costs sibling by positioning itself as the matching step before import, so an agent can identify its role without opening schemas.

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 a clear use case ('match a seller's per-product shipping file to exact SKUs/ASINs before building import_fbm_costs rows') and explains the fbmOnly/missingOnly filtering modes. It does not explicitly name exclusion cases or contrast with all sibling worksheet tools, but the intended workflow is clear.

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