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

Beyond the annotations (which already declare read-only, idempotent, non-destructive, closed-world), the description adds cost ('free'), auth requirements ('no authentication'), the transport shape ('one cheap HTTP GET'), and error semantics ('ok is false when unreachable rather than raising'). Those are exactly the traits an agent needs and none are derivable from structured fields.

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?

Three short blocks — what it is, what it costs, when to call it — with the identity statement front-loaded and the conditional guidance last. Every sentence carries distinct information and none repeats the annotations or the schema.

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?

An output schema exists, so return shape need not be described, and the description covers the remaining unknowns: cost, auth, failure mode, and sequencing relative to payment tools. For a zero-parameter liveness probe this is complete.

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?

There are zero parameters, so per the baseline this scores 4; there is no parameter meaning to add or omit. The description correctly spends no words on an empty argument object.

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 first line states a specific verb and resource ('Service status and liveness check'), and the description explicitly separates it from `execute_task` for liveness purposes. An agent can distinguish it from siblings like `get_job_status` or `get_credit_balance` 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?

It gives an explicit precondition ('call before `price_task` or `execute_task`'), an explicit branch on the result ('If ok is false, do not attempt payment'), and names the alternative it replaces ('Use this instead of `execute_task` for liveness'). This is the full when/when-not/alternative triad.

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