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

Annotations already cover readOnly/idempotent/non-destructive, and the description layers on real behavioral context beyond them: the required read scope, run_* matching semantics ('none means no run was recorded'), and the deliberate omission of delivery error text. It also explains the untrusted_fields marker, which is not derivable from annotations or schema.

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-loads the scope requirement, then purpose, then output details. Dense but every clause earns its place (event list, matching rule, omission, untrusted_fields). Slightly heavy as a single block, but no wasted sentences.

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?

With no output schema, the description carries the return-value burden and does so thoroughly: it enumerates timeline event types, explains the run-matching rule, notes omitted error text, and defines untrusted_fields. An agent can interpret the response without further documentation.

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 coverage is 100% and the single incident_id parameter is already documented with its source (list_incidents, list_open_incidents, add_incident_note). The description adds no further parameter detail, 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?

States a specific verb and resource ('Gets one incident and its ordered timeline'), clearly distinct from the list_incidents/list_open_incidents siblings which return collections. The enumerated event types make the scope concrete rather than generic.

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?

Gives a clear purpose framing ('For what the run was doing, who was paged and what was tried'), which tells the agent what questions this tool answers. It does not explicitly name alternatives such as get_run or list_incidents, so routing 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.