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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds meaningful non-annotation context: the operation is 'Owner-scoped' (an access constraint) and returns per-source chunk counts plus first/last indexed timestamps, which compensates for the missing output schema. It stops short of covering pagination or ordering, so not a 5.

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?

Two sentences, front-loaded with the core action and scope. The parenthetical field list and the sibling-routing clause each earn their place; nothing is restated from the name or annotations.

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 carries the burden of explaining returns and does so by naming the grouped fields, chunk counts, and timestamps. It is nearly complete, but omits whether the listing is paginated, sorted, or bounded in size.

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?

There are zero parameters, so the baseline is 4. The description correctly implies no filtering arguments are needed, though it could have explicitly noted there are no inputs.

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 states a specific verb and resource: 'List what is currently indexed in the user's private knowledge base', then enumerates the grouping fields and metrics. It explicitly distinguishes itself from mRAG_search and mRAG_delete, so an agent can route without opening sibling schemas.

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?

It gives two concrete use cases: seeing what mRAG_search can recall, and finding a source_id to pass to mRAG_delete. The alternatives are named and the condition that selects this tool versus search/delete is unambiguous.

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