List tool namespaces

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description goes beyond them by disclosing the grouping derivation (mount prefix from server.py) and the ordering of results ('most populated first'), which 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?

Front-loads the one-line summary, then separates mechanics, usage, exclusion, and return shape into labeled blocks. Every sentence carries information; nothing is redundant filler.

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?

An output schema exists, yet the description still usefully previews the return shape and ordering. With zero params, full annotation coverage, and an explicit alternative-tool pointer, an agent has everything needed to select and invoke this correctly.

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 the baseline is 4 and there is nothing to document. The description does mention the `namespace` parameter, but that belongs to the sibling discover_tool_search rather than this tool, so it adds no semantics for this call's own (empty) input.

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 every mounted Nexus tool namespace with its tool count') and adds the aggregation logic (grouping by mount prefix). An agent can distinguish this from sibling list tools like entities_list_entities or discover_tool_search without opening a schema.

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?

Explicit 'Use when' clause ties it to pre-narrowing a discover_tool_search call, and a 'Not for' clause routes the agent to discover_tool_search with a namespace when it wants tools inside one domain. Both the positive and negative cases are covered with a named alternative.

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