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

With annotations only declaring the safe-ish write profile, the description adds substantive context: Bearer auth via PRIVI_WRITE_KEYS and the PRIVI_ALLOW_LOCAL_WRITES=1 gate for stdio. It stops short of saying what appending does to the lot's status (e.g. a 'recalled' event) or whether duplicate events are allowed.

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?

Three tight sentences, front-loaded with the core action and audience, then the auth prerequisites. Every sentence carries information; no padding or repetition of the schema.

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 7-parameter mutation tool with no output schema, the definition omits the return value and any effect on downstream state (chain of custody, lot verification). Auth and audience are covered, but an agent still lacks a full behavioral picture before writing.

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 86%, so the schema already explains lot_code, event_type, location, actor, and the optional fields. The description adds no syntax, format, or enum guidance beyond that, so the baseline 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?

'Append an event to a lot's history' names a specific verb and resource, which reads clearly as a write operation distinct from read-oriented siblings like privi_verify_lot and privi_chain_of_custody. It does not explicitly name or contrast with any sibling though, so an agent must infer the boundary.

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 '(manufacturers only)' qualifier and the PRIVI_WRITE_KEYS requirement give real gating context, but there is no explicit when-to-use guidance and no routing against the other privi_* tools. Usage is implied rather than stated.

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