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

Annotations already provide readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral context: authentication requirements (Bearer or X-API-Key), the non-guest restriction, and the fact that it returns instructions/calldata rather than mutating state. No contradictions with 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?

Four short sentences front-load the core purpose and then add necessary prerequisites, auth, return contents, and REST endpoint. Every sentence contributes distinct information with no redundancy.

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 a single well-documented parameter, safety annotations, and no output schema, the description provides all essential context: what is returned, how to authenticate, who may call it, what must exist first, and a free alternative. Nothing critical is missing.

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 100%; the session_id param is already well described as a UUID of an opened data session from data_session_open. The description only repeats the 'opened data session' prerequisite and adds no additional parameter-level detail, so baseline 3 is appropriate.

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 a specific action: 'Buy per-query access to live data listings' and clarifies the deliverable as 'funding instructions and createEscrow calldata'. It also references data_preview for free access and requires an opened session via data_session_open, distinguishing this tool from siblings.

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 gives explicit context: use data_preview for a free taste and use this with a session opened by data_session_open. It also warns 'Not guest-callable'. However, it does not explicitly contrast with data_session_fund or data_session_attach_escrow, leaving some alternative routing implicit.

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