chat_history_append

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

With only readOnlyHint: false, annotations are minimal. The description fully discloses the write behavior, filesystem target, return value ('returns the written entry plus its resolved target path'), safety validation ('path outside the allowlist... raises an error before writing'), and the dry_run side-effect-free preview. This goes well beyond what annotations provide.

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 four sentences, front-loaded with the primary action, then usage context, then safety/behavior specifics. Every sentence adds critical information: what it does, when to use it, the write behavior and safety, and the dry_run escape hatch. No wasted words.

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 6-parameter write tool with no output schema and minimal annotations, this description is remarkably complete. It covers the target file locations, the return payload, path restrictions, dry_run behavior, and downstream consumers. An agent can confidently select and invoke this tool without further clarification.

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 baseline is 3. The description adds meaningful behavioral semantics for the 'path' parameter (allowlist and traversal checks) and clarifies dry_run's purpose. It also explains the entry body ('text') in the context of a JSONL log, enhancing understanding beyond the schema's bare field descriptions.

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 states the tool's purpose: 'Append one structured entry to the consumer project's chat-history log (a JSONL file).' This is a specific verb+resource that distinguishes it from siblings like chat_history_read, which retrieves the log, and other memory tools that operate on different stores.

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 explicitly says 'Use to record a decision, note, or phase marker that should persist into a later session or be distilled by `mine_session`.' This gives clear context for when to use the tool. It also notes back-compat paths and the dry_run option, but it does not explicitly state when not to use it (e.g., for ephemeral or non-history data), so it falls 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.