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

Beyond the annotations it discloses that results are a cached snapshot ('as the gateway last listed them'), that per-scope listings may carry a failure reason, that a 'refreshing' scope means a background re-list was triggered by a never-listed/changed/hour-old condition, and that a personal API key is required. These are exactly the traits the annotations cannot express.

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?

The purpose and caching semantics are front-loaded, and every clause carries information (union, per-scope, refresh state, auth). The middle segment ('the union, and per scope the tools that scope's credential lists, or why it could not') is dense to the point of being hard to parse on a first read.

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 still conveys the return shape (union plus per-scope entries plus failure reasons plus refresh markers) and the auth prerequisite. For a single-parameter read tool that is everything an agent needs to call it and interpret the result.

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% for the single parameter, and the schema already explains that the slug comes from list_gateway_servers and how it prefixes agent-facing tool names. The description adds nothing parameter-specific, 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?

The description names a specific verb and resource ('List the tools a gateway server's downstream advertises') and pins the data to what 'the gateway last listed', which separates it from the catalog-style siblings such as list_tool_catalog and list_tool_definitions. It never names those siblings explicitly, so an agent must infer the boundary, which keeps it below 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?

'Use the names for set_agent_tool_access and pipeline conditions' gives concrete downstream usage, and the 'refreshing ... call again shortly' clause tells the agent how to react to a transient state. It stops short of naming alternatives or stating when not to use this tool, so no exclusions are offered.

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