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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds domain behavior — that Headed In alerts a boater's people when overdue, and that Headed Back has no check-in — which helps an agent reason about the subject matter, but says nothing about the tool's own call behavior or return format.

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?

It is front-loaded with 'Our two free apps' and then splits cleanly between the two products, which is good structure. However, the long parenthetical catalogue of games ('the license plate game, Swamp Ape Millionaire, trivia, critters caught only at real places, The Daily Humidity') does not help an agent select or invoke the tool and pads the second sentence.

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 parameters, no output schema and only read-only annotations, this is a simple informational tool, and the description does describe both subject apps thoroughly. What it omits is the tool's own contract: what a call returns (text, links, app metadata) and how it relates to 'open_plan_in_app'.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate. Baseline 4 applies for a parameterless tool with an empty object schema.

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?

The description clearly identifies the resource: the two apps, 'Headed In' (a boat float plan with back-by time and overdue alerts) and 'Headed Back' (road-trip games and trivia with no check-in). An agent can tell what content this tool covers, though it never states an explicit verb such as 'returns descriptions of' and never says what the call actually yields.

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?

There is no when-to-use or when-not-to-use guidance. The sibling 'open_plan_in_app' exists and is obviously related, but the description never says whether this tool explains the apps versus launching one, so the agent must infer the distinction.

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