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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, yet the description still adds genuinely new operational facts: no file reads, no shared folder required, and no credit consumed. That cost/side-effect disclosure is exactly the value-add structured fields cannot carry.

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?

Two sentences, front-loaded with the outcome and followed by the safety/cost rationale. No filler and nothing that could be cut without losing information.

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, and the description only loosely indicates the return ('how long a round trip takes') without saying whether reachability is a boolean, whether latency is milliseconds, or what happens on failure. Combined with fully undocumented parameters, the definition is adequate but leaves real gaps for a 3-parameter tool.

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 all three parameters (echo, device_id, workspace_id) are undocumented, so the description must compensate and does not. It never explains what 'echo' does, whether device_id is effectively mandatory despite zero required fields, or how workspace_id scopes the lookup.

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 and resource ('Check that a device is reachable') plus the measured result ('how long a round trip takes'), which is clearly distinct from siblings like device_tool_call and health. It stops short of naming those siblings, so the differentiation is implicit rather than explicit.

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 is the safe way to prove a device is live' implies when to reach for it, but there are no explicit exclusions and no alternatives are named (e.g. when to use health or device_tool_call instead). An agent gets a hint of context, not a routing rule.

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