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

Annotations already declare readOnly=true, destructive=false and closed-world, and the description adds the meaningful behavioral note that this is optional and non-blocking. It does not say whether repeated calls are idempotent, whether receipts expire, or what happens if the receipt is stale — gaps that matter for an acknowledgment-style call.

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 payload, followed by the optionality caveat. Nothing is padded and no clause is wasted.

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 two-parameter, closed-world, no-output-schema acknowledgment call, the description covers the essentials: what it does, what it consumes, and that skipping it is safe. Remaining ambiguity (idempotency, stale receipts) is minor at this complexity level.

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%, with both opaque parameters already documented as coming from the read response and the final part. The description only restates their presence ('with its read_id and receipt') and adds no format, lifetime, or sourcing detail beyond the schema, 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 action (acknowledge the final part of a multi-part Arroway read, supplying read_id and receipt) and that it closes the sequence. It is distinguishable from sibling arroway_read by being the terminal acknowledgment step, though it never names arroway_read as its predecessor explicitly.

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?

Usage is implied rather than stated: an agent infers it should call this after the final part of a multi-part read returns a receipt. The one explicit guideline is an exclusion ('It is not a precondition for working'), which usefully says when not to bother, but there is no 'use when the read response is incomplete' instruction or mention of what to do with siblings like arroway_continue.

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