vault_append

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

Goes well beyond the annotations: it discloses create-on-miss behavior, mandatory optimistic concurrency on existing files, the LF normalization side effect, binary/NUL rejection, and the absence of automatic retry. These are exactly the mutation traits an agent needs and annotations alone don't convey.

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 compact sentences with the primary action and create-on-miss behavior front-loaded, then constraints. No filler; each clause carries a distinct operational fact.

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?

An output schema exists so return values needn't be described, and the mutation semantics are well covered. The remaining gap is the missing pointer to where ifMatchGuard/versionGuard values come from (presumably vault_read) and what failure looks like when the precondition fails.

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 description coverage is 0%, so the description must carry the load. It clarifies the conditional requirement on ifMatch/ifMatchGuard ('copy versionGuard'), but leaves the sha256 format of ifMatch, the 64MiB content cap, and where a guard token is obtained unexplained.

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 ('Append UTF-8 text') and adds a key scope fact — missing files are created. The append semantics are self-evidently distinct from siblings like vault_write, vault_patch, and vault_replace_text, though no sibling is named.

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 real conditions ('Existing files require ifMatch or ifMatchGuard') but frames them as parameter requirements rather than when-to-use-this-vs-alternatives guidance. An agent still must infer that vault_write is the overwrite path and vault_patch the edit path.

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