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

Annotations already declare readOnlyHint=true and destructiveHint=false, indicating no state mutation. The description adds that it 'Returns fund instructions after data_session_open,' clarifying the operational flow. No contradiction; the description aligns with annotations and adds sequence context.

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?

Two sentences, no filler. The main purpose is front-loaded, the specific listing and price are given, and the dependency on data_session_open is mentioned. Every sentence contributes to effective tool selection and invocation.

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 single-parameter tool with no output schema, the description covers purpose, pricing, and sequencing. It could explicitly compare with data_session_fund or data_session_attach_escrow, but the existing content is sufficient for an agent to use it correctly.

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?

The schema provides a description for session_id (UUID from data_session_open) and the description reiterates the sequencing, but adds no new syntax or format details. Schema coverage is 100%, so the description only marginally supplements the parameter explanation, matching the baseline.

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 tool's purpose: 'Buy per-query access to live data listings' and specifies the exact listing (mitwatch) with pricing. It also distinguishes itself by mentioning the sequence (after data_session_open) and the free alternative (data_preview), making it easy to understand its role relative to 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 context on when to use it (after opening a data session) and mentions data_preview as a free first step, but it does not explicitly contrast with other funding tools like data_session_fund or data_session_attach_escrow. The guidance is implicit rather than a clear decision tree.

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