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

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=false, so the agent knows this is a non-destructive write. The description adds only that it is retrospective booking; it says nothing about duplicate-entry risk (implied by idempotentHint=false), permission prerequisites, or what happens if both projectId and projectName are supplied.

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, front-loaded with the action and fields, then the differentiator. There is no filler or redundancy.

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 6-parameter, 1-required mutation tool with a fully documented schema and no output schema, the description covers purpose, field set, and the main sibling distinction. It stops short of noting validation behaviour or how projectId/projectName interact, which would matter at invocation time.

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 description coverage is 100%, so the baseline is 3 and the schema already explains date format, hour range, and that projectName is used to look up projectId. The description only reiterates which fields are optional, adding little beyond the structured data.

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 ('Books') plus resource ('worked hours') and enumerates the core fields (hours, date, description, optional customer/project). The final clause explicitly separates it from the live time clock, which is exactly the sibling set (clockIn/clockOut/endBreak) an agent could confuse it with.

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?

'After the fact' plus 'Separate from the live time clock' gives a clear when-to-use condition and a when-not alternative. It doesn't address the correction path (updateTimeEntry) for fixing an already-booked entry, so the guidance is strong but not complete.

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