memory_update

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

With no annotations, the description carries the full behavioral burden and discharges most of it: it discloses that the old content is destroyed, that an automatic backup happens before the write, and gives the exact guardrail (reject if new content <1KB and less than a third of the old content) plus its rationale (防写坏, corruption prevention). Missing only edge details such as where the backup lives, whether the guard can be overridden, and required permissions.

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?

One dense sentence plus a parenthetical: target and semantics first, then the backup and guardrail details. No filler and no repetition of the tool name.

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 need not be explained here, and the destructive-write risk plus the safety guard are well covered for a one-parameter overwrite tool. What is absent is prerequisite/permission context and any indication of what happens on a rejected write (error shape, backup location).

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 single 'content' parameter has 0% schema description coverage, so the description must compensate. It does convey that content is the complete replacement text for FACT.md and hints at a size floor (<1KB triggers the guard), but it never states format expectations (markdown?), total-replacement vs merge, or encoding.

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 in the first three words: '覆盖写入 FACT.md（长期记忆）' (overwrite FACT.md, long-term memory). The overwrite semantics inherently separate it from the sibling memory_append (incremental add) and the read-only memory_read/memory_search, so an agent can route correctly 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?

The word '覆盖写入' (overwrite) implies this tool replaces the whole file, which indirectly signals that memory_append is the alternative for incremental additions. However, no sibling is named and there is no explicit when-to-use / when-not-to-use statement, so the routing is left to inference.

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