things_health

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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds genuinely new behavioral context beyond them: it surfaces that the response reports read-only mode and tracking policy, which tells the agent whether write operations (the siblings) will actually succeed. It doesn't mention failure modes or error behavior, keeping it out of 5 territory.

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?

A single front-loaded sentence with no filler. Every listed item (availability, identity, read-only mode, tracking policy) is a distinct piece of information the caller needs, so nothing could be cut without loss.

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?

There is no output schema, so the description carries the return-value burden — and it does so by enumerating the four things the check reports. That is enough for an agent to know what it will learn, though it says nothing about the shape/format of those values or how a negative result (e.g., Things unavailable) is represented.

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?

Zero parameters, so there is nothing to document and the schema coverage is 100% by definition. Baseline 4 applies; no parameter-level information is missing.

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 gives a concrete verb ('Check') and enumerates exactly what is inspected: local Things availability, server identity, read-only mode, and tracking policy. That scope is unmistakably a diagnostic/health tool and cannot be confused with the CRUD siblings (create/list/get/update/move/schedule/complete). It stops short of a 5 only because it never explicitly frames itself as the status/diagnostic entry point relative to those 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?

Usage is implied rather than stated: a 'health' tool is obviously for pre-flight/status checks, but the description never says when to call it (e.g., before mutating operations, after a connection error) or what to do with the result. No alternatives or exclusions are named, so the agent must infer the trigger condition.

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