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

Despite annotations already marking it read-only, the description discloses what the annotations cannot: the result is a cached snapshot ('as the gateway last listed them'), the background refresh semantics for scopes marked refreshing with a retry hint, that failures are reported per scope with reasons, and that a personal API key is required. This is substantive behavioral context beyond the structured fields.

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?

Every sentence carries information and the listing/refresh/retry points are ordered logically, but the opening sentence is densely packed with colon-separated clauses that take a second read. No filler, only slight structural overhead.

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 output schema, the description does the work of describing returns (the union plus per-scope lists and failure reasons), and it covers auth and refresh behavior. It is nearly complete; only the exact shape of the per-scope failure payload is left implicit.

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% and the single server_slug parameter is already well documented in the schema, including its origin (list_gateway_servers) and the <slug>__<tool> prefix. The description adds no parameter-level detail, so the baseline 3 applies.

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 the tools a gateway server's downstream advertises, by their own names') and pins the scope to a single gateway server, which separates it from catalog-wide siblings like list_tool_catalog. It never names an alternative tool, so an agent still has to infer the routing on its own.

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?

Gives a concrete downstream use ('Use the names for set_agent_tool_access and pipeline conditions') and a retry instruction for scopes marked refreshing. It stops short of stating when NOT to use it or naming a sibling to prefer instead, so it is clear context without explicit exclusions.

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