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

Annotations already declare readOnlyHint=false, so the mutation behavior is known. The description adds 'Free' and 'keeping your own state tidy', which are motivational rather than behavioral. It doesn't contradict annotations but adds little beyond what the schema and annotations already convey.

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 short and action-oriented, front-loading the core purpose. However, the 'Free' aspect is mentioned twice ('Free — keeping...' and 'Price: Free'), which is redundant. The structure is clean with clear sections, but the redundancy detracts slightly.

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 simple one-parameter delete tool, the description covers the action, usage, and pricing. It doesn't describe return values or side effects, but given the simplicity and annotations, nothing critical is missing. It is complete enough for an agent to use correctly.

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 only mentions 'key' implicitly as the stored item to delete, providing minimal meaning about what the key represents. It doesn't explain format, constraints, or how to identify a valid key. The description adds little beyond the schema's type definition.

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 the verb 'Delete' and the resource 'a stored key', making the tool's purpose immediately clear. It distinguishes from siblings like memory_get, memory_set, and memory_search by specifying the delete action.

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 description provides a clear usage condition: 'Call when a stored fact is stale or wrong.' It does not explicitly mention when not to use it or name alternatives, but the context is clear enough to guide an agent. This meets the 'clear context, no exclusions' level.

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