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

The 'WRITE:' prefix and the prerequisite routing are useful, and 'Nothing existing is changed' clarifies the additive write scope. But that sentence directly conflicts with the annotation destructiveHint=true, leaving an agent with contradictory safety signals about a write operation. No mention of what is returned or how duplicate logs are handled.

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 clauses, front-loaded with the operation class ('WRITE') and the resource, then the valid input shapes, then the prerequisite. No filler and nothing to cut.

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 an 11-parameter create tool with no output schema, it covers the operation class, the two input modes and the required dependency. It leaves unaddressed whether billable entries need contact/project, but the schema's per-field descriptions and defaults carry that load adequately.

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 baseline is 3; every parameter is already documented inline. The description does add real value by stating that date+duration and start+end are mutually exclusive input modes, a relationship the schema only hints at with '(with start)' / '(with duration)'.

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 and resource ('log time in bexio'), with the resource made explicit by the tool name and the timesheet domain. It implicitly separates itself from the mutating siblings by noting 'Nothing existing is changed', though it never names bexio_list_timesheets or an update tool as the alternative.

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?

Gives the two valid input shapes ('either date + duration (HH:MM), or start + end') and the hard prerequisite ('Needs a business activity (bexio_list_business_activities)'), naming the exact tool to call first. It stops short of stating when not to use this tool (e.g. when logging against an existing entry).

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