health_check

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

With no annotations, the description carries the full burden and does well: it discloses the read-only diagnostic nature, the six items inspected, and the OK/WARN/ERROR output format. It stops short of stating that it makes no mutations or that it may be slow when the vault or embedding server is unreachable.

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-loaded purpose in the first sentence, then a compact list of checks, then the return format. Every clause carries information an agent can act on; there is 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?

For a zero-parameter diagnostic with an output schema already describing the report structure, this covers what the agent needs to decide and call the tool. The only gap is the absence of guidance on when this is preferable to narrower siblings like index_stats.

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, which is the baseline 4 case; the description correctly does not invent argument semantics, and the empty schema needs no compensation.

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+resource ('Diagnose second-brain system health') and then enumerates the exact checks performed, so an agent can distinguish it from operational siblings like index_stats, sync_index, or auth_context without opening any 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?

Use is implied by the diagnostic framing, but there is no explicit when-to-use guidance, no statement of when-not-to-use it, and no routing to alternatives such as index_stats or query_audit_log for narrower diagnostics.

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