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

Annotations already declare non-readOnly, non-destructive behavior, but the description adds important context the annotations cannot: that only labels are mutable and the memory text is immutable, plus the correction workflow via add_memory. It doesn't mention permission or auth requirements, so it isn't exhaustive.

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?

Two tight sentences: the actionable scope comes first, followed by the key limitation and its alternative. Every clause carries information and there is no filler.

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?

With annotations covering safety and an output schema covering returns, the description supplies the one non-obvious rule an agent needs — text immutability — making it largely complete. Minor gaps remain around auth or failure behavior, but nothing critical is missing for correct invocation.

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 100%, so the schema already documents each parameter including replace-vs-clear semantics for tags and reserved-key handling for metadata. The description only echoes the field names without adding syntax or format detail, making 3 the right baseline.

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 names a specific verb ('Change the labels') and resource ('an existing memory'), then enumerates the exact mutable fields (tags, importance, metadata, source, event_type). This clearly separates it from siblings like add_memory and delete_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?

It explicitly states the boundary condition — the memory text cannot be edited — and routes the agent to add_memory for corrections, which is a genuine alternative with a selecting condition. It doesn't address broader routing against get_memory or delete_memory, so it falls short of a full when/when-not map.

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