patch_day

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

With no annotations, the description carries the burden and does well: it discloses the UI-navigation mechanics ('navigate to its week ... save'), the strict single-day blast radius, and the return shape including 'before/after'. It does not state what happens when the target day was never saved, nor any auth or lock/approval preconditions, which is the remaining gap.

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?

Three short sentences, front-loaded with purpose and scope, then the return contract, then the parameter constraint. No filler; every clause carries decision-relevant 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 3-parameter mutation with no annotations and no output schema, the description supplies both the return shape and the safety boundary, which is most of what an agent needs. Missing only edge-case behavior (target day not yet saved, locked or approved periods) that would matter for correct invocation.

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 0%, so the description must compensate and only partly does: it clarifies the hours/comment mutual-requirement ('at least one of') and that date selects the target week. It adds nothing about hours units/rounding, whether a comment can be cleared given minLength 1, or what an omitted field means (leave unchanged vs. clear).

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+resource+scope: 'Correct a single already-saved day for the configured project'. The explicit negative 'Does NOT touch any other day' plus the 'single day' framing cleanly separates it from month-level siblings like draft_month and apply_month.

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?

'Correct a single already-saved day' tells the agent this is an edit of existing data, not a create, and 'Provide at least one of hours/comment' gives an invocation precondition. It stops short of naming the alternative to use for bulk corrections or new entries, leaving sibling routing partially inferred.

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