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

With no annotations, the description carries the full burden of behavioral disclosure. It states the tool checks health and configuration and notes 'Free,' but does not clarify read-only nature, authentication needs, rate limits, or potential side effects. The read-only aspect is implied by 'check' but not explicitly stated.

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 description is extremely concise, containing one meaningful sentence plus a standalone 'Free.' It is front-loaded and under 20 words, but the 'Free' fragment adds minimal value and could be ambiguous. Otherwise, it is well-structured.

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 simple no-parameter health check with an output schema, the description is largely complete. It clearly states what the tool does, and the output schema covers return details. However, it lacks any information about usage frequency or cost implications beyond 'Free,' which is a minor gap.

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 has zero parameters, and the input schema already reflects this with an empty object. Per the rubric, 0 params yields a baseline of 4, and since no parameters exist, the description need not add anything further. The baseline is appropriate.

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 uses the specific verb 'check' with the resource 'health and configuration of this service,' making the purpose unambiguous. It distinguishes itself from sibling tools like brain_session_status or brain_check_balance by focusing on service-level health and configuration.

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?

The description provides no guidance on when to use this tool versus alternatives. It does not mention any exclusions, complementary tools, or typical scenarios, leaving the agent to infer usage from the name alone.

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