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

With no annotations, the description carries the burden and does add useful behavior: visibility access rules and key reuse restriction. However, it does not disclose what happens on key conflict with different content (overwrite vs. error), nor any return/confirmation behavior, which is notable for a write tool.

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 with no wasted words. The core action is front-loaded, followed by the most decision-relevant parameter guidance and a key conflict warning.

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?

Covers the main invocation decisions: what to persist, how to scope visibility, and key reuse. However, with no output schema and no annotations, an agent is left guessing about the exact effect of reusing a key with changed content and what success looks like. Slightly more disclosure would make it fully complete.

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 compensate. It explains visibility semantics and key reuse, and the phrase 'memory or instruction' maps to the kind enum. Title and body are self-explanatory, but not every parameter's nuance is explicitly detailed.

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 ('Persist') and resource ('a memory or an instruction for future agents'), and distinguishes the two modes. This cleanly differentiates write_memory from siblings like read_memory, list_memories, and update_memory.

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 clear operational guidance: use visibility=shared for future arrivals, default private restricts to author/admin, and reuse a key only for identical retries. It does not explicitly name alternatives or when-not-to-use conditions, but the context is sufficient for typical selection.

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