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

readOnlyHint=true is already declared, so the safety profile is covered. The description adds genuinely useful context the annotations cannot carry: the hash output is an optimistic-concurrency token to be returned as expectedHash, and a contract doc must be consulted first. It stops short of stating pagination/caching or how 'exists:false' behaves.

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-loads the action and the returned fields in one compact sentence, then adds the workflow rule. Every clause carries information, though the trailing 'Rules:' line is slightly fragmentary and could be folded into the preceding sentence for cleaner structure.

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 an output schema present, the field list in the description is confirmatory rather than necessary, and the description still supplies the workflow context (read-before-write, hash round-trip, required contract doc) an agent needs to call this correctly in sequence.

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?

There are zero input parameters, so there is nothing for the description to clarify about inputs; the schema baseline of 4 applies. The mention of 'hash' and 'expectedHash' concerns the sibling tool's parameter, not this one's, so it does not raise or lower the input-semantics score.

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+resource ('Read the site-wide stylesheet (global.css)') and even enumerates the returned fields (css, exists, bytes, url, hash). This clearly separates it from sibling fabrement-get-global-js and from the write counterpart fabrement-save-global-css without opening any schema.

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 'Read before save-global-css; pass hash back there as expectedHash', naming the workflow dependency and the alternative it feeds. Adds a further prerequisite ('read get-skill-doc {id:"global-css-contract"} before the first call'), so when-to-use is fully specified with no inference needed.

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