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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the agent knows this is a safe, non-idempotent write. The description adds that times are optional but does not say what happens on duplicate bookings, whether a non-matching workerName/projectName is created or errors, or what the call returns — meaningful gaps for a mutation tool with no output 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?

A single front-loaded sentence that names the resource, its purpose, and the optional time fields with no wasted words. It could be slightly stronger if it used the remaining space for a when-to-use clause instead of restating optionality.

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 output schema, the description covers the core intent but leaves out what is returned, error behavior for unresolved names, and any planbook preconditions. Since annotations cover the safety profile and the schema covers every parameter, the remaining gap is moderate rather than critical.

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%, so the schema documents all nine parameters including date/time formats and the workerName/projectName ID-resolution note. The description only adds that startTime and endTime are optional, which is already inferable from the required list, so it does not meaningfully exceed the baseline for fully documented schemas.

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 gives a specific verb and resource ('Creates a planbook assignment') plus the key dimensions of the record — team member, project, date, optional times. It is clearly distinguishable from updateAssignment by the 'Creates' verb, though it never explicitly contrasts the two.

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 guidance on when to use this versus updateAssignment, no prerequisites (e.g., whether a planbook or project must already exist), and no exclusions. Usage is only implied by the name and the create verb.

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