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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered structurally; the description reinforces it and adds workflow context about how the selection is applied later. It stops short of describing how the user 'picks' (UI vs. subsequent call), leaving one behavioral gap.

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 sentences, zero filler, with the read-only constraint front-loaded immediately after the purpose. Every clause earns its place.

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?

With no output schema, the description correctly states what comes back (3 pairings). It is complete for invocation, though it could clarify the interplay with suggest_palettes, since the schema also accepts a palette.

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%, so the baseline is 3, but the description adds a real constraint beyond the schema: the font families must be Google Fonts and pair as heading + body. That meaningfully narrows valid values for headingFontFamily/bodyFontFamily.

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 gives a specific verb and resource ('Show 3 font pairings (heading + body Google Fonts)') and states the return cardinality, so an agent knows exactly what this produces. It distinguishes itself from set_theme by naming it as the follow-up tool, though it does not explicitly contrast with the sibling suggest_palettes.

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 states the negative condition ('Does NOT change the site') and names the alternative path ('the chosen pairing is applied separately with set_theme'), which is exactly the when/when-not/alternative structure. An agent cannot misroute this as a mutation.

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