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

Annotations already cover readOnly/destructive/openWorld, yet the description adds genuinely non-obvious behavior: it works without Obsidian running, and it returns count 0 rather than erroring when no vaults exist. The closing `permissions` explanation adds meaning but is dense and partly duplicates the output schema.

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 first two sentences are tight and front-loaded, but the trailing sentence about `permissions`, the LMCP settings path, and read_only is long, nested and only loosely tied to calling the tool, so it does not fully earn 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?

With an output schema present and zero input parameters, the description only needed to cover purpose and entry-point routing, which it does. It slightly over-delivers by re-explaining the return payload's `permissions` field that the output schema already defines.

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 no parameters, so there is nothing to disambiguate and the baseline of 4 applies. The description correctly spends no space on argument semantics and instead describes the response payload.

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 ('Lists the Obsidian vaults on this computer') and enumerates the returned fields (id, name, folder path, note count), which distinguishes it cleanly from obsidian_read_note, obsidian_search_notes and obsidian_write_note.

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?

'Start here: the other obsidian_* tools take a vault name or id from this list' explicitly routes the agent to this tool as the entry point and names the dependents. It also states a precondition ('Obsidian does not need to be running') that would otherwise cause an agent to skip the call.

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