list_capabilities

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 genuinely new context beyond the annotations: it needs no workspace, and it discloses that the payload includes each agent's descriptor (backend tools, permissions, payload keys, declared outputs).

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?

Front-loaded with the purpose in the opening clause, followed by scope and the usage trigger. The first sentence is dense with parentheticals, which slightly slows reading, but every element earns its place.

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 zero-parameter, no-output-schema discovery tool, the description fully covers what it returns (capabilities, providing agents, operations, agent descriptors) and its usage trigger. Nothing needed to call it correctly is missing.

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 and schema coverage is 100%, so there is no parameter semantics for the description to carry. Baseline of 4 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+resource ("List what this Gateway can do") and then defines what a capability actually is with concrete examples (java.decompile, android.rebuild, instrument.trace). It also names what is returned (agents, operations, descriptors), so an agent can distinguish this discovery tool from the action-oriented siblings.

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 an explicit trigger: "Use it to discover what is available, for example when a plugin might provide something the other tools don't." That is clear when-to-use guidance, but it names no specific sibling or exclusion, so it stops short of the routing precision of a 5.

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