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

Annotations already declare this as mutating, non-destructive, and idempotent. The description adds meaningful behavioral context beyond annotations: authentication requirements, guest-call restrictions, REST endpoint, and the preference order for the escrow identifier. No contradictions with annotations are present.

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 sentences deliver purpose, free alternative, auth constraints, field preference, guest restriction, and REST endpoint with zero filler. Every clause earns its place and the most important information is front-loaded.

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?

Given no output schema and moderate operational complexity, the description is largely complete: it specifies the endpoint, required session context, auth, guest exclusion, and the preferred optional parameter. The only gap is that it does not describe what the response contains or how to obtain a funded escrow, but this is arguably covered by sibling tools and the invocation context.

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 only 33%, so the description must compensate. It does: it explains session_id as an opened session, identifies open_tx_hash and proof_escrow_id as alternative buyer-funded proof escrow references, and states that open_tx_hash is preferred. This adds meaningful selection semantics beyond the raw schema, though it does not fully detail the exact format of each identifier.

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?

The description clearly states the operation: attach a buyer-funded proof escrow to an opened data session to buy per-query access. It names a specific verb and resource, and explicitly contrasts with data_preview ('first taste free'), helping distinguish from sibling tools.

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 provides clear usage context: when you have an opened session and want paid access, use this tool; use data_preview for a free taste. It also states prerequisites (agent API key, not guest-callable) and field preference (open_tx_hash preferred over proof_escrow_id), though it does not explicitly contrast with data_session_fund or data_session_funding_package.

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