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

Annotations already provide readOnlyHint=false, destructiveHint=false, and idempotentHint=true, so the operation's safety profile is covered. The description adds useful context beyond annotations: authentication requirements, guest restriction, and preference for open_tx_hash over proof_escrow_id. It does not contradict annotations.

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 cover purpose, free alternative, auth, guest restriction, parameter preference, and REST endpoint without wasted words. The value proposition is front-loaded and every sentence earns its place.

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 3-parameter mutation tool with annotations and no output schema, the description covers prerequisites, alternatives, parameter preference, and endpoint. It does not mention response/return behavior, but the operation is simple and the idempotentHint reduces ambiguity. Overall, it is sufficiently complete for correct invocation.

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 only 33%, so the description must compensate. It clarifies that open_tx_hash is preferred over proof_escrow_id and that both relate to a buyer-funded proof escrow. It does not fully explain the provenance or exact format of these identifiers, but it provides meaningful guidance beyond the schema.

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 states the action explicitly: 'Attach a buyer-funded proof escrow ... to an opened data session.' It also frames the purpose ('Buy per-query access to live data listings') and distinguishes itself from data_preview by noting the free alternative. The verb+resource is unambiguous.

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?

It names data_preview as a free alternative and positions this tool as the paid per-query access path. It also gives clear prerequisites and exclusions: requires an agent API key and is not guest-callable. This tells an agent when to use it and when not to.

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