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

Beyond the annotations (which only declare non-read-only, idempotent, non-destructive), the description discloses the authorization model (assignee, recorder, or workspace owner), the resulting state change visible in engramic_timeline and the app, and a full error-code table including FORBIDDEN_NOT_AUTHOR and NOT_FOUND. This is exactly the context annotations cannot carry.

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?

Front-loaded with the action and its effect, then a usage sentence, then a scannable error-code list. The phrase 'in engramic_timeline and in the app' is slightly redundant but nearly every line earns its place.

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 mutation with no output schema, the description covers purpose, trigger, permission rules, observable effect, and every failure mode. An agent has everything needed to call it correctly and interpret failures.

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%, with both eventId and note already documented including the max length and id pattern. The description adds only that the note is optional and that an over-long note yields VALIDATION_ERROR, 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 and resource ('Mark an action done, with an optional note') and scopes the operation to actions only ('Only actions can be completed'), which separates it from the many create/update record siblings. It stops short of naming an alternative tool for other record types, so it is clear but not fully sibling-differentiated.

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?

'Use this when the user says an action recorded earlier is finished' gives a concrete trigger condition for invocation. It does not state when NOT to use it or point to a specific sibling for non-action records, leaving that to inference from the FORBIDDEN/VALIDATION errors.

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