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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds useful provenance (values come from chartory.css) and mode-resolution semantics, but never says what the response looks like — flat name/value pairs, grouped object, raw CSS text — which matters since no output schema exists.

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 dense sentences that front-load the resource and then the two knobs, with no filler. The CSS-selector clause is slightly jargon-heavy but it is the only place that semantics is explained.

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 two-parameter read tool this covers source, modes, and filtering, but with no output schema the description should say how tokens are returned (shape, whether values include fallbacks/var() references). That omission leaves a real gap for an agent composing a call.

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 baseline is 3, but the description earns more: it explains what the mode enum actually means (light = :root, dark = .dark, data-theme scopes a subtree) and gives concrete filter fragment examples ("data", "surface", "signal") that the schema lacks.

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 the exact resource (Chartory design tokens / CSS custom properties from chartory.css), the mode dimension, and the optional name filter, so an agent knows precisely what it gets back. It doesn't explicitly name the chart-oriented siblings, but the resource is distinct enough that confusion is unlikely.

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?

Usage is only implied: fetch tokens when you need design tokens. There is no statement of when to prefer this over the chart siblings, or when to use one mode rather than another (the :root/.dark/data-theme note explains mechanism, not selection policy).

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