get_brightness

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and locality are covered by structured data. The description's only added behavioral fact is the return format (percentage), which is genuinely useful given there is no output schema, but nothing is said about failure modes (no backlight available, display vs. external monitor) or whether the value is a raw device percentage.

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?

One sentence, front-loaded with the verb, and every clause (current, screen, percentage) earns its place. Nothing to trim.

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 zero-parameter read tool with annotations covering safety and openWorld, the description plus annotations cover nearly everything an agent needs: what it returns and that it is a safe read. Only minor edge-case behavior (which display, what happens with no backlight) is unaddressed, which is acceptable for this complexity.

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 takes zero parameters, so per the baseline rule this scores 4. The description correctly makes no parameter claims and instead spends its words on the return value.

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?

States a specific verb ('Get') and resource ('current screen brightness') plus the return unit ('as a percentage'). It is implicitly distinct from set_brightness/increase_brightness/decrease_brightness, but never names them, so sibling differentiation relies on naming convention rather than on the description itself.

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 read-only nature of 'Get' implies when to use it, and the sibling set makes the read-vs-adjust split obvious, but the description never explicitly says 'use this to check brightness before/after adjusting' or excludes any alternative. Usage is inferred, not stated.

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