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

With no annotations, the description carries the full behavioral burden and does well: it discloses the TTL delta, the hard lifetime cap, a payment/cost requirement, and the failure mode that expired memories are deleted and non-extendable. It omits error behavior for unknown/invalid ids and whether the operation is idempotent.

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 short sentences, front-loaded with the core action and constraint, then payment requirement, then failure case. No filler; every sentence carries new information.

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 one-parameter tool with no output schema, the description covers cost and lifecycle limits well but leaves the id semantics and the outcome of a successful call (e.g., new expiry) unstated, so the agent cannot fully predict the result.

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 sole parameter 'id' has 0% schema description coverage, so the description must compensate. It only implies that the parameter identifies the memory; it says nothing about id format, source, or what an invalid id does.

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 (extend a memory's TTL) with concrete scope: +30 days, capped at 365 days from creation. The operation is clearly distinguishable from siblings like store_persistent_memory and read_memory without opening the 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?

Gives useful preconditions (requires x402 payment, expired memories cannot be extended), which implies when the tool is applicable. However, it never names an alternative or tells the agent when to extend versus re-create a memory with store_persistent_memory; 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.