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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description adds value by noting the prerequisite session from data_session_open and that it returns fund instructions. It does not disclose side effects beyond that, but the annotations cover the safety profile. The description is consistent with annotations (no contradiction) and adds a modest behavioral detail.

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, front-loaded with the core purpose and specific listing details. No fluff; every word earns its place. The flow hint (data_preview and data_session_open) is integrated efficiently.

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 annotations and no output schema, the description covers the essential action, the specific listing, and the flow. It doesn't detail the format of the returned fund instructions or error handling, but these are minor for a tool that returns instructions rather than executing a purchase. Overall, it's sufficiently complete for an agent to call 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?

Schema coverage is 100% with a clear description for session_id ('UUID of a data session you opened'). The tool description only reiterates that it comes from data_session_open, adding no new meaning beyond the schema. Baseline 3 is appropriate since the schema already fully explains the parameter.

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: buying per-query access to live data listings. It names a specific listing (govulnwatch) with price, and references data_preview for free taste and data_session_open for the prerequisite flow. This distinguishes it from siblings like data_preview and data_session_open, though not from data_session_fund explicitly.

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 some usage context: preview via data_preview, then open a session, then this tool returns fund instructions. However, it does not explicitly contrast with data_session_fund or data_session_attach_escrow, leaving the agent to infer when to choose this over those siblings. It implies a sequence but lacks explicit exclusions.

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