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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds value beyond that by confirming the tool 'never signs, settles, or interprets a payment' and that payment/job status live elsewhere, which sets clear expectations about side effects and scope.

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, zero filler, and the primary capability is front-loaded before the scope limitation. Every clause carries information: service list, resource contracts, pricing, policy links, and the payment boundary.

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?

Return values need not be explained because an output schema exists, and the description still previews what the payload contains. With no inputs, strong annotations, and an explicit scope boundary, everything an agent needs to call this correctly is present.

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 are zero parameters, so there is nothing for the description to compensate for; the baseline for a no-param tool is 4. The description correctly avoids describing inputs and instead frames the tool as parameterless discovery.

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 a specific verb and resource: discovering Sourcey's enabled paid agent services and canonical HTTP resources, with concrete payload contents (request/response contracts, price floor, policy links, x402 discovery). It is clear on its own but never differentiates itself from sibling tools like search_offers or compare_offers, which also concern paid offerings.

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?

Usage is implied rather than stated: an agent infers this is the entry point for enumerating available paid services. The one explicit boundary clause ('Payment and durable job status remain on the product HTTP API') is a useful when-not, but it points outside the MCP server rather than routing to a sibling tool, and no when-to-use condition is given.

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