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

With no annotations, the description carries the full behavioral burden and does so well: it discloses the ownership requirement, the important null-clears semantics for trigger_url, trigger_auth_header, and skill_id (versus omitting a field), and the side effect that changing schedule_cron recomputes the next run time and is re-validated against a plan floor. It omits failure/error behavior and whether connector_ids replaces or merges, which keeps it off a 5.

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 sentences, front-loaded with the action and ownership, with the parameter list and the schedule_cron side effect following. Dense but every clause earns its place; the parenthetical '(null clears)' notes are load-bearing.

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 nine-parameter mutation tool with no annotations, no output schema, and 11% schema coverage, the description covers nearly all parameters and the key side effect. It leaves some error/return expectations and connector_ids replacement semantics unstated, but an agent has enough to invoke it correctly.

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 only 11%, so the description must compensate, and it largely does: it enumerates all eight optional parameters and clarifies the null-clears behavior that the bare schema cannot express. Gaps remain for payload structure and whether connector_ids is a full replacement or a merge.

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+resource ('Update a routine') and adds an ownership scope ('you own') that distinguishes it from sibling mutations like create_routine, delete_routine, and run_routine. It stops short of explicitly naming those siblings as alternatives, but the verb is unambiguous.

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?

'Pass any subset of...' gives real guidance on partial-update invocation, and 'a routine you own' implies the prerequisite. However, there is no explicit statement of when to reach for this tool versus create_routine/run_routine/delete_routine, so routing is only implied.

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