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

Annotations already declare this is a non-read-only, non-destructive, idempotent mutation, so the safety profile is covered. The description earns credit above that baseline by disclosing the state transition ("the task returns to open"), which is exactly the behavioral fact an agent needs to predict the effect; only error/edge behavior on an already-open task is left unstated.

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 short sentences with zero filler, and the core effect (returns to open) is front-loaded before the id prerequisite. Nothing could be removed without losing information.

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 single-parameter, non-destructive mutation with full annotation coverage and no output schema, the description supplies the effect, the reversal relationship, and the id source, which is nearly everything needed. Only edge-case outcome (task already open) is unaddressed, a minor omission given idempotentHint=true.

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 schema property already states "A task id from get_today: <program id>|<yyyy-MM-dd>|<task path>." The description's "The task id comes from get_today" merely repeats that, adding no format or provenance detail beyond the structured field, 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?

"Undo a skip: the task returns to open" gives a specific verb (undo skip) plus the resulting resource state, so an agent can distinguish it from skip_task and complete_task without opening the schema. It stops just short of 5 because it never explicitly contrasts itself with skip_task, relying on the name to imply the inverse relationship.

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?

Usage is implied by "Undo a skip" and the definition helpfully names get_today as the required source of the id, which is real routing guidance. It offers no explicit when-not condition (e.g., what to do if the task is already open, or to use complete_task when the goal is completion), so an agent must infer the boundary.

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