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

Annotations only flag readOnly=false, destructive=true, openWorld=false; the description adds the substantive detail behind that destructiveness — frontmatter is regenerated (custom frontmatter lost), the supplied name/description/instructions must be complete replacements, and a Personal Space is written/created as a side effect. Those are exactly the consequences an agent must know before a destructive write.

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?

Three sentences, purpose first, then the alternative path, then the space side effect — no filler. It is dense and packs several clauses per sentence, which costs a little readability but not correctness.

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 description needn't explain returns, and it covers the mutation semantics and space default well. The notable gap is source_refs: for a full-replacement write, an agent is not told whether omitted source_refs are dropped, which matters given destructiveHint=true.

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 38%, so the description must carry more weight, and it does explain the space_id default ('Personal Space unless space_id names another, creating Personal when needed'). However, expected_version_id is only named, never explained as an optimistic-concurrency check, and source_refs and idempotency_key are not addressed at all in the description.

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 and resource ('Save a new version of a private skill') and immediately names the exact inputs that define the operation (knowledge_id, expected_version_id, complete name/description/instructions). It distinguishes itself from knowledge_update, the closest sibling, in the same sentence.

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?

Gives an explicit routing rule: if you need to preserve custom frontmatter, use knowledge_get + knowledge_update instead. That is a concrete when-to-use-alternative statement. It does not say when to choose skill_create vs skill_update, leaving that boundary to the name.

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