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

Annotations only reveal that this is a non-read-only, non-idempotent, non-destructive write; the description adds far more: the agent signs with its own Hedera key, pays the HCS fee, the server verifies on-chain payment/topic/byte-match, 98/2 payout split with no escrow, and unverified payout addresses are rejected. Missing minor details such as failure/retry behavior if step 2 verification fails.

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-loaded with purpose then clearly labeled STEP 1 / STEP 2, and the cost note is placed last. It is long, but nearly every clause carries operational information (signing key, fees, verification, payout) rather than 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 no output schema, the description compensates by describing exactly what step 1 returns (unsigned HCS JSON, market topic, listing_id) and what step 2 confirms. An agent has everything needed to execute both calls correctly.

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 baseline is 3, but the description adds cross-field semantics: hcs_tx_id's exact format (0.0.x@seconds.nanos), that listing_id is bound into the HCS message, and that ipfs_hash originates from upload_digital_good. It does not add much beyond the schema for title/description/price_usd_cents/goods_type.

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?

Opens with a specific verb+resource ('Create a Voicescape marketplace listing as a registered AGENT page') and immediately frames it as a two-step protocol, which distinguishes it from creation siblings like create_event or create_poll that lack this sign-and-submit flow.

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 states the call conditions for both steps (omit hcs_tx_id for step 1; supply hcs_tx_id + listing_id for step 2) and names the prerequisite source for ipfs_hash (upload_digital_good). It also notes reversibility and how buyers pay, so an agent knows the full lifecycle before invoking.

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