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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutation profile is covered. The description adds two pieces of context not in the annotations: default-memory immutability and zero credit cost. It does not explain what 'destructive' means concretely (e.g. that rescoping replaces the prior scope), so it stays at a baseline-plus level.

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, front-loaded with the operations, then the immutability caveat and cost note. No filler; every clause carries information the agent needs.

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 an output schema present the description needn't cover return values, and annotations cover the safety profile, so the remaining burden is small. It covers operations, the immutability constraint and cost; it omits only minor detail such as whether unspecified fields are left unchanged.

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 name, scope, situation and memoryId fully. The description's verbs ('rename', 'rescope', 'update its situation') loosely mirror the three optional params but add no format or constraint detail beyond the schema — the baseline 3 when the schema does the heavy lifting.

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 set and resource: 'Rename or rescope an existing named memory, or update its situation.' Each operation maps cleanly onto an editable field, and the phrase 'existing named memory' distinguishes it from create_memory and list_memories without the agent 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?

Gives a clear precondition/exclusion — 'The default memory is immutable' tells the agent when this tool will fail — plus a cost signal ('no credits consumed'). There is no explicit routing sentence naming create_memory or list_memories as alternatives, which keeps it short of a 5.

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