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

Annotations declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, openWorldHint=false. The description adds that it returns fund instructions after data_session_open, which is useful return-flow context beyond the annotations. However, it doesn't clarify directionality (it appears to be a read that yields instructions rather than a mutation), leaving some ambiguity against the readOnly annotation.

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 sentence is cluttered with promotional phrasing ('first taste free') and an embedded listing advertisement, burying the actual function. Structure is not front-loaded on the verb-action.

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 tool whose role in the funding flow is unclear relative to its siblings, the description omits prerequisites, sequencing, and outcome. Given no output schema and several sibling funding tools, it should clarify how it relates to data_session_fund and data_session_attach_escrow.

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 single session_id parameter is fully documented in the schema (UUID from data_session_open). The description adds no parameter-level detail, so baseline 3 applies.

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 action (buy per-query access) on a specific resource (live data listings), naming the concrete listing and its price. It reads more like a marketing blurb than a definition, but the resource is unambiguous. It does not clearly distinguish itself from data_session_fund or data_session_attach_escrow, the closest 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?

It mentions a free 'first taste' via data_preview and references data_session_open, but gives no explicit when-to-use-vs-alternatives guidance. Nothing tells the agent how this differs from data_session_fund or data_session_attach_escrow, so tool selection among the funding siblings is left to inference.

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