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

Annotations already cover readOnly=false, idempotent=true, destructive=false, so the safety profile is partly structured. The description adds genuinely non-structured context: cost ($0.25), payment rail (USDC on Base or Arbitrum One), a paid URL, and the privacy model ('You keep the document; we never see it'). It does not restate the idempotency behavior, which the schema already handles.

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?

The core purpose is front-loaded, but '$0.25' appears twice (once as a bare price, once restating 'Paid tool — $0.25'), and the paid URL is duplicated framing. The repetition costs space without adding information.

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?

An output schema exists, so return values need not be explained. For a paid mutation-style tool, the description covers cost, payment chain, and privacy, which is enough for correct invocation. Minor gap: no statement of latency/turnaround for the attestation or what the receipt contains beyond 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 description coverage is 100% and the schema fully documents document_hash, document_name, and idempotency_key, including the UUID v4 and replay semantics. The description's mention of SHA256 overlaps with the schema rather than extending it. Baseline 3 is appropriate when the schema carries the parameter burden.

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: it timestamps a document's SHA256 hash into a signed attestation proving existence at a point in time. The mechanics ('we timestamp your document's SHA256 hash') are concrete. It does not explicitly distinguish itself from siblings like attest or prove_it, which appear to overlap in the timestamping/proof space.

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 by 'proof your document existed at a point in time,' giving the agent a clear scenario, but there is no explicit when-to-use vs. when-not, no prerequisites, and no named alternative among the sibling tools (attest, prove_it, trust_report). The agent must infer selection.

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