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

Annotations already declare destructiveHint=true, idempotentHint=false and readOnlyHint=false, so the mutation/irreversibility profile is covered structurally. The description adds useful context beyond that: the enumeration of mutable bag-level facts and the scope boundary against update_bean. It does not, however, warn about downstream effects of state changes (freshness/age computation) or note that omitted fields are untouched.

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 tight sentences: what it changes, where bag numbers come from, and the sibling split. Front-loaded with the operation and 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?

With an output schema present and annotations carrying the safety profile, the description supplies everything an agent needs to select and call this tool: scope, id provenance, field-level intent mapping, and the boundary against update_bean. Remaining per-field details (grams_remaining/weight_adjustment_g interactions) are already documented in the schema.

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 67% with a large nested fields object, and the description compensates by naming the concrete bag-level facts (roast date, weight, grams left, price) and by mapping user intent verbs (open/seal/freeze/thaw/finish) onto the underlying state field. That adds meaning beyond the raw schema, though it doesn't cover reason or weight_adjustment_g 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?

Specific verb ('change') plus a clearly scoped resource ('bag-level facts on one bag of a coffee'), and it enumerates the concrete operations (open, seal, freeze, thaw, finish, correct roast date/weight/grams/price). It explicitly distinguishes itself from update_bean for coffee-level attributes, so an agent can route without opening either schema.

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 the alternative tool and the condition that selects it ('For the coffee itself — roaster, origin, roast level, rest window, notes — use update_bean'), and tells the agent where valid bag_ids come from (bags[] on list_beans or current_bag_id). Nothing is left to inference.

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