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

The description reveals that the operation is financial ('Buy per-query access,' 'buyer-funded') and requires authentication ('Requires an agent API key,' 'Not guest-callable'), adding behavioral context beyond the annotations (e.g., idempotentHint). It does not contradict the 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?

The description begins with extraneous marketing ('Buy per-query access to live data listings — first taste free via data_preview') and only later states the core action. This is not tightly front-loaded and could be more concise.

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?

The description includes the REST endpoint, auth requirements, and the main action, providing enough context for a simple attach operation. It lacks details about response format, but no output schema is expected, so this is adequate.

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?

With only 33% schema description coverage, the tool description adds meaning by clarifying that 'open_tx_hash preferred, or proof_escrow_id' are alternative parameters, reducing ambiguity about which to provide. It also reinforces that session_id refers to an opened session.

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 primary action: 'Attach a buyer-funded proof escrow ... to an opened data session.' It uses a specific verb ('attach') and resource ('escrow to data session'), which distinguishes it from siblings like data_session_open and data_session_fund.

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 gives contextual guidance by mentioning the prerequisite of an 'opened data session' and notes alternatives such as 'first taste free via data_preview.' It also states auth requirements ('Requires an agent API key') and that it is 'Not guest-callable,' which helps decide when to use this tool.

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