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

With no annotations provided, the description carries the burden of behavioral disclosure. It does disclose a key behavioral trait: 'History is never mutated,' which is important for an append operation. However, it does not mention other behaviors such as idempotency, duplicate handling, or failure semantics, leaving some gaps.

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 two short sentences with no wasted words. The core operation is front-loaded, and the behavioral guarantee is stated immediately after, making it easy to parse quickly.

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 append operation with full schema coverage and an output schema, the description is largely complete. It states the core behavior and the most important guarantee (history immutability). It could be slightly stronger with usage context, but nothing critical is missing.

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 all parameters thoroughly. The tool description adds no new parameter-level meaning beyond what is already present, which matches the baseline for full schema coverage.

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 clearly identifies the action and resource: 'Append one event to a stream.' It is specific enough to distinguish from read-only siblings like event_list, though it does not explicitly differentiate from other append-like tools such as memory_session_append.

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 implies the tool is for recording a new event in a stream and notes that history is never mutated, which gives some context for when it is appropriate. However, it provides no explicit guidance on when to choose this tool over alternatives like event_list or memory_session_append.

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