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

Annotations only mark readOnlyHint=false; the description goes far beyond by disclosing the preview/validation/diff/confirmationToken flow, that 'replace' deletes every absent line, and the OAuth + OWNER role requirement. These are exactly the mutation and destructive-behavior details an agent needs before calling.

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 purpose, then the two-step mandate, then mode semantics, then prerequisites — a logical order with no filler sentences. It is a single dense paragraph with heavy parenthetical nesting, which slightly hurts scanability.

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?

For a mutation tool with no output schema, the description supplies what's needed: it describes the preview's return (per-line warnings, a diff, a token), the confirm flow, the merge/replace consequences, and auth requirements. Nothing essential to calling it correctly 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 already 83%, so the schema carries most parameter meaning; the description adds value by explaining zone containers ('one rate for every country of it without a rate of its own'), the 'ALL' zone for packing/picking, and that the commit call must repeat the SAME account/mode/rows plus the token. It largely restates zone/kind semantics already in the schema, so not a full 5.

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 (Import) and resource (FBM rate book) with scope 'ONE account', and enumerates what the rates cover (shipping per container/country/ROW, packing per parcel, picking per unit). It is unmistakably clear what the tool does, though it never names a sibling (e.g. import_fbm_costs) to distinguish itself from.

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 this is the FIRST thing to set up and 'nothing is priced until a zone rate exists', mandates the two-step preview-then-commit flow, and explains when to pick 'merge' vs 'replace'. The conditions that select each behavior are spelled out, not implied.

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