append_event

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

Goes well beyond the annotations by disclosing that the log is append-only and hash-chained server-side and that history cannot be rewritten via SQL, which is meaningful durability/immutability context not present in the hints. It still does not describe the response, error behavior, or concurrency implications for a non-idempotent write.

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 action and its immutability guarantee come first, then the usage trigger. No wasted words and the most decision-relevant fact (append-only, cannot be rewritten) is front-loaded.

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 two-parameter, single-required write tool with no output schema and no nesting, the description covers action, immutability, and usage sufficiently for correct invocation. Only the return behavior and failure modes are left unstated, which is a minor gap at this complexity.

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 both 'kind' and 'content' are already documented, including the example labels for kind. The description's mention of decisions/results/errors/observations loosely echoes the kind values but adds no format, length, or constraint detail beyond the schema, so the baseline of 3 applies.

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 (append) and resource (one entry to the memory log), which is precise enough to separate it from siblings like write_query and checkpoint. It does not explicitly name an alternative tool, so it falls short of full sibling differentiation.

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?

Explicitly says when to use it: 'for decisions, results, errors and observations worth remembering across sessions,' which gives the agent a clear content-based trigger. It offers no when-not guidance and does not route the agent to or away from specific siblings such as checkpoint or write_query.

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