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

Annotations only declare write/idempotency/destructive flags; the description adds the important fact that this call mutates a second resource (feed assets inventory), and that confirm toggles commit vs dry-run preview. That goes beyond structured fields. Note a mild tension with idempotentHint=false, which suggests the key-based validation is not guaranteed retry-safe, but this is a clarification gap rather than an outright contradiction.

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 short sentences, front-loaded with the action and its side effect; no filler. The second sentence is slightly vague ("supports ... validation" without saying what validation enforces) but is not wasteful.

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 covers the primary effect, the dry-run mechanism, and the idempotency concept, while the rich 9-parameter schema handles the rest. Missing: what a dry-run returns and whether permissions or inventory prerequisites are required, both minor given the schema coverage.

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 description coverage is 100%, so the schema already defines all nine parameters including confirm, idempotencyKey, lbsPerBag defaults, and numeric bounds. The description only names confirm and idempotency without adding format, constraints, or interaction rules, so baseline 3 applies.

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 and resource ("Log a feed purchase") plus the key side effect ("automatically increment feed assets inventory"), which distinguishes it from read-only siblings like get_feed_inventory. It does not explicitly name or contrast with other log_* siblings, but the resource is narrow enough that an agent can place it correctly.

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 mentions "confirm and idempotency validation," which implies a dry-run-first workflow and a safe-retry path, but it never states when to use this tool versus alternatives or what conditions require idempotencyKey. Usage is implied 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.