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

With no annotations, the description carries the behavioral burden. It does disclose that the operation appends to the end of an existing document, implying existing content is preserved, but it omits behavior for nonexistent documents, whether changeNote is stored, and what the return/confirmation looks like. The schema mentions the blank-line separator, not the description.

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 short sentences with no filler. The core operation is front-loaded, and the second sentence adds a concrete use case rather than restating the schema.

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?

The tool is simple and the description captures its primary behavior, but with no output schema, no annotations, and a mostly undocumented schema, the agent still lacks return/error behavior and changeNote semantics. The required parameters and use cases are at least inferable, making the definition minimally workable.

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?

Only one of the three properties (content) has a schema description, so the description must compensate for documentId and changeNote; it does neither. ChangeNote's meaning and format and documentId's identification role remain undocumented from both description and schema.

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 uses the specific verb 'Append', identifies the resource ('existing text document'), and specifies position ('end'), so an agent can distinguish it from create_document and update_document. It stops short of explicitly naming a sibling for replace-style edits, but the operation is unambiguous.

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?

The sentence 'Useful for ongoing notes, decision logs' gives explicit intended contexts for the tool. It does not state when not to use it or name alternatives like update_document, but the guidance is clear for common append scenarios.

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