Current Active Vault

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

Annotations already declare readOnlyHint and idempotentHint, and the description reinforces this with 'Read-only.' It adds real value beyond annotations: enumerates the reason values (session-selected/env-default/none), discloses the failure condition ('tools will fail until vault.select or an env var is set'), and explains the obsidianLiveInstance note. Consistent with annotations, no contradiction.

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 description is dense, not terse, but every sentence earns its place: scope, reason semantics, failure mode, and workspace distinction are all load-bearing for correct use. Slightly heavy for a zero-param introspection call, but not padded.

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?

Completely adequate for a zero-parameter read-only tool. The description covers what is returned, the meaning of each reason value, the failure condition when nothing is configured, and the live-process caveat. Nothing an agent needs 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 has zero parameters and the schema is empty with 100% coverage, so the baseline is 4. The description compensates by documenting the return semantics (reason field values and obsidianLiveInstance note), which is more useful than parameter documentation for this introspection tool.

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: 'Return the vault that filesystem tools would resolve to right now, plus the full precedence chain.' The enumerated filesystem tool families (notes.*, tags.*, dataview.*) and the explicit contrast with vault.list/vault.select/vault.reset make its role unambiguous among 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?

Explains when the tool matters (to explain why a vault was picked) and clarifies the boundary with workspace.*/commands.* tools, which target the live process vault instead. It doesn't name an explicit alternative for when-not-to-use, but the live-vs-filesystem distinction is clear guidance.

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