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

Beyond annotations (already covering readOnly/idempotent/non-destructive/openWorld), the description adds genuinely useful traits: the payload is often 30k–60k characters, so callers should anticipate large responses and subset via sections. It also explains that provenance.source (bundled/static/community) is distinct from transport origin and includes an explicit caveat that coverage guidance does not certify visual quality or accessibility.

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?

Front-loaded: purpose, then the warning about payload size, then the subsetting rule. The Args block partly duplicates the schema, but Returns and the two Examples each carry distinct information, so nearly every line 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?

For a two-parameter read tool with a full output schema, the description supplies everything else an agent needs: when to call it, the size hazard, the subsetting lever, the section vocabulary, provenance semantics, and a caveat about what the payload does not guarantee.

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; the description goes further by enumerating the twelve valid section values inline and repeating the omit-for-full-brief behavior. This gives an agent the selection vocabulary without opening the schema, though it adds no format constraints beyond what is structured.

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 opens with a specific verb and resource: 'Fetch one complete implementation contract before generating UI,' and clarifies the bundled payload (rules, CSS, templates, recipes, tokens). It implicitly differentiates from token/recipe-only siblings by emphasizing the 'in one call' bundle and the optional sections subset, but it never names a sibling tool explicitly.

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 a clear trigger ('Use this when you need the full rules, CSS, templates, recipes and tokens in one call') and gives a narrowing strategy ('Pass sections to return only identity/provenance plus the parts you need'), reinforced by two concrete examples. It stops short of naming when to prefer a sibling tool such as stylekit_get_style_tokens instead.

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