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

Annotations already mark the tool as idempotent and non-destructive. The description adds the fact that funding is platform-executed and implies a payment transaction, which is useful context. However, it does not disclose any auth, rate limits, or effects on the session beyond enabling queries.

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 is two sentences and reasonably front-loaded with the core purpose. However, the specific listing example ('registerwatch: The Register — Enterprise IT & Sysadmin Headlines') adds detail that may be too concrete for a generic tool definition and slightly distracts from the general function.

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 the simple one-parameter schema, no output schema, and the annotations, the description covers the basic purpose and points to the contiguous query step. It does not, however, clarify how this tool relates to the similarly named funding_package and attach_escrow siblings, leaving a meaningful context gap in the broader session-funding workflow.

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?

There is a single session_id parameter with full schema description coverage at 100%. The description adds no extra meaning for the parameter, so the 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?

The description states a specific verb and resource: 'Buy per-query access to live data listings' and 'Platform-executes funding so you can data_session_query.' It clearly identifies this as the funding step for a data session, though it does not explicitly distinguish itself from the sibling 'data_session_funding_package.'

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 hints at usage by saying the first taste is free via data_preview and that funding enables data_session_query, but it gives no explicit when-to-use or when-not-to-use guidance and does not mention alternatives like data_session_attach_escrow or data_session_funding_package. The routing to the correct sibling is left mostly to inference.

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