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

With no annotations, the description carries the behavioral disclosure burden. It discloses the 10240-byte cap, the 413 over-cap response, and the warning that replace is riskier than append. It does not explicitly state that all previous memory content is discarded, but 'replace the entire memory file' strongly implies it.

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?

The description is three sentences with no filler: the operation, the usage warning, the trigger conditions, and the cap/error are all packed in. The most important guidance is front-loaded with 'USE SPARINGLY.'

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 single-parameter tool with no output schema, the description provides everything needed: what it does, when to use it, when not to use it, the size limit, and the failure response. No critical context appears missing.

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?

The schema already documents the single 'content' parameter at 100% coverage, including its Markdown format and the empty-string-to-clear behavior. The description reinforces that the content replaces the entire file and adds context about size limits, but it does not add substantial parameter meaning beyond the 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 states a specific verb and resource: 'Replace the entire memory file for the calling user.' It also distinguishes itself from the append alternative by explicitly calling append 'the safer primary,' so an agent can tell the two operations apart.

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?

Usage guidance is explicit and actionable: 'USE SPARINGLY,' append is preferred, and replace should only be called when memory has drifted wrong, accumulated stale entries, or the user requests a clean rewrite. This clearly routes the agent between replace and append.

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