vault_stats

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: the deprecation lifecycle (v2.x callable, removal in v3.0.0) and the all-vaults default, which an agent cannot infer from the schema or annotations.

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?

Three tight sentences: capability first, scope/usage second, deprecation last. Every clause carries information (return contents, default scope, migration target, timeline) with no 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?

With no output schema, the description must carry return-value semantics, and it does so by listing the metrics returned. Combined with the deprecation notice and usage routing, an agent has everything needed to decide whether to call this or switch to the resource.

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 0% and the single `vault` parameter is undocumented in the schema. The description compensates by explaining its omission semantics ("Omit `vault` to get all configured vaults"), which is real meaning beyond the structured field, though it never states the accepted identifier format for the parameter.

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 enumerates exactly what the tool returns (note/word counts, top tags, frontmatter keys, embedding model, last index run) and frames it as agent self-orientation, which is far more specific than a restatement of the name. It lacks an explicit verb, and overlap with siblings like list_models/index_runs/list_vaults is only implicitly resolved by the enumerated contents, so it stops short of 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?

It states when to use the tool (agent self-orientation/discovery), how to widen scope ("Omit `vault` to get all configured vaults"), and routes the agent to a named alternative (the `vault-memory://stats/{vault}` MCP Resource), including the migration timeline. Nothing about tool selection is left to inference.

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