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

No annotations are provided, so the description carries the full behavioral burden. It discloses price and seller but does not explain what happens when the tool is invoked: whether it creates a contract, executes immediately, requires registration, or how the resulting xlsx is delivered. For a marketplace tool, this is a significant transparency gap.

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?

Three short sentences with zero filler. The action and price are front-loaded, followed by the key deliverable. 'Sold by Sphere' is compact but conveys provenance. Every sentence earns its place; the structure aids quick parsing.

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?

With no annotations and no output schema, the description is too thin to fully guide an agent. It doesn't explain the purchase lifecycle, how results are retrieved, or how this relates to the sibling marketplace_* tools (e.g., marketplace_accept_contract, marketplace_get_result). The service context and expected follow-up steps are missing, making the description incomplete for a 5-parameter marketplace operation.

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%, so parameters are already documented to a baseline level. The description adds value by clarifying that task_payload should contain 'headers and rows with typed cells,' which maps to the actual service input better than the generic schema examples. This slightly exceeds the baseline but doesn't deeply elaborate on parameter formats.

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 names the specific resource (create_xlsx) and states its function: 'Send headers and rows with typed cells.' It is distinguishable from sibling buy_* tools by the service name and emitted artifact. However, 'Buy' as the leading verb focuses on the purchase action rather than the underlying spreadsheet-creation service, so the purpose is clear but slightly indirect.

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?

There is no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites, the marketplace contract flow, or how this buy path compares to marketplace_create_contract, x_payment, or other buy_* siblings. The intended usage must be inferred entirely from the tool name and bare description.

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