get_computed_style

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

Describes return format (per-element property→value maps) and scope. Lacks details on edge cases (no matches, errors) but no annotations exist, so description does reasonable job. Could mention safety/read-only nature.

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: first defines operation, second provides usage guidance. No redundancy or fluff.

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?

Describes output format sufficiently for a simple read tool. Could mention default max_results or handling of multiple elements, but overall adequate given parameter count and schema coverage.

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 covers 100% of parameters with descriptions. Description does not add extra parameter-level detail beyond schema, but reinforces purpose. Baseline 3 justified.

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?

Clearly states it reads computed CSS values (rendered), specifying verb 'Read', resource 'CSS values', and context 'after stylesheets and inheritance'. No sibling offers this, so it's well-differentiated.

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?

Explicitly says to use for programmatic verification of colors, fonts, spacing, display, opacity instead of screenshots. Provides clear use case and alternatives (screenshot tools).

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