list_services

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds cost information not present in annotations ('FREE') and discloses the payload contents (prices, limits, notices, examples), which is meaningful beyond the structured fields; it does not cover pagination or ordering of results, but the tool is a small static catalog.

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 short sentences with zero waste, and the highest-value fact (free) is front-loaded before the contents list and the call-ordering directive.

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?

No output schema exists, so the description carries the burden of describing the response, and it does so concretely (price in USDC, limits, notices, example requests). An agent has everything it needs to call this correctly; only minor details like result count or ordering are absent.

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 tool takes zero parameters, so there is no parameter syntax to explain and the baseline is 4. The description instead spends its words on what the caller receives, which is the right trade-off here.

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?

States a specific verb and resource ('List all paid data services') and enumerates exactly what each entry contains: price in USDC, limits, notices, and example requests. That scope clearly separates it from the sibling tools, which are individual paid data endpoints.

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?

'Call this first' is an explicit ordering directive that tells the agent when in the workflow to reach for this tool. It doesn't name any alternatives or exclusions, but as a catalog/discovery entry point there is no real alternative to disambiguate against.

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