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

readOnlyHint=true already tells the agent this is a safe read, so the lower bar applies. The description still adds real value by disclosing that the call is 'Free' (no cost/credit consumed) and by enumerating exactly which fields constitute the 'full' payload, which the annotation cannot convey.

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?

One sentence, front-loaded with the resource and its scope, then the returned fields, then the cost caveat. Every clause carries information; nothing is padded or repeated from the name.

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 one-parameter read tool with no output schema, the description is sufficient: it enumerates the return contents thoroughly and states that the call is free, which is the main behavioral fact an agent needs before invoking it.

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% and the single parameter is a closed enum of four service names, so the schema already does the work. The description never mentions the 'service' argument or how to choose among drop/ai/decide/image, so it adds nothing beyond the schema — baseline 3.

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?

'One service in full' plus an explicit enumeration of what comes back (MCP URL, config snippet, HTTP routes, prices, limits, security model) makes the tool unmistakably a single-service detail fetch. It implicitly contrasts with list_services via 'one service ... in full', but never names the sibling, so it stops short of a 5.

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 only implied: an agent can infer 'call this when you need details on one specific service.' There is no explicit when/when-not statement and list_services is never mentioned as the alternative for discovery, so routing between the two is left to inference.

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