update_time_entry_until

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

Goes well beyond the annotations by disclosing non-obvious mechanics: hours are computed locally as end_time - start_time, only hours and start_time are transmitted, end_time is never sent to the server, end_time must be strictly after start_time, and ongoing is always forced to false. For a destructive mutation this is exactly the operational detail an agent needs.

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?

Front-loaded with the distinguishing behavior, then two short sentences on the computation and the validation constraint. No repetition of the schema and no filler.

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?

Covers the distinctive mechanics well and the confirm preview semantics live in the schema. What is missing is the effect on fields not mentioned (does the existing duration get cleared, does ongoing=False overwrite an in-progress entry), which matters for a destructive, open-world mutation.

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 13% (just the confirm parameter), so the description has to compensate. It adds real meaning for start_time and end_time (validation rule, local computation, server never receives end_time) but says nothing about time_entry_id, user, comment, activity, or spent_on.

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 first sentence states a specific verb (Update) and resource (time entry) plus the key differentiator: it takes start/end time instead of a duration. That implicitly separates it from update_time_entry and create_time_entry_until, though neither sibling is named explicitly.

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?

"Instead of a duration" clearly tells the agent when to pick this over update_time_entry, and the reference to update_time_entry's docstring points at the alternative for duration-based edits. There is no explicit when-not guidance, but the selection context is clear.

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