Get or set display brightness

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

No annotations are provided, so the description carries the burden. It discloses the read/change modes and the external-display failure behavior, which goes beyond the schema. Could add return format details, but the disclosure is effective.

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 concise sentences are front-loaded with the core purpose and quickly give behavior and limitations. No waste or 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 one-parameter optional tool with no output schema, the description covers purpose, invocation mode, and a key error case. It doesn't explicitly state the return value, but 'it only reports' implies this adequately.

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 coverage is 100%, and the schema already documents level as an optional 0-100 percentage. The description's '0 to 100' and 'Called with no arguments it only reports' reinforce the schema but do not add substantial new parameter semantics.

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?

Description states 'Read or change the built-in display brightness' with specific verb+resource and a clear 0-100 scope. It distinguishes this from audio/volume and other tools by explicitly targeting the built-in display.

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?

Clearly defines when it reads vs changes: 'Called with no arguments it only reports' and warns external displays will error. Does not explicitly name alternative tools, but context is sufficient for this simple tool.

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