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

Beyond the destructiveHint annotation, it discloses non-obvious behavior: the API derives the missing third time field, billing role/work type/billable status are inherited from the ticket rather than supplied, and retrying after an unclear error risks duplicate entries. That duplicate-write hazard is exactly the operational risk an agent needs to know before calling a write tool.

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?

Four short sentences, front-loaded with the "WRITE:" marker and the resource, then the invocation rule, then defaults, then the retry hazard, then the endpoint. Nothing is redundant with the schema or title.

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?

With 8 params, 100% schema coverage and no output schema, the description covers the risky parts (field derivation, inherited defaults, duplicate risk). It does not say what a successful call returns, which matters somewhat given there is no output schema to fall back on.

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 field meaning is already documented; the baseline would be 3. The description earns above baseline by adding a cross-parameter rule absent from the schema: required is 0, yet exactly two of started_on/ended_on/actual_hours must be supplied and the API computes the third. It does not explain user_id defaulting or billable_status_id fallback behavior in any more detail than the schema.

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?

"WRITE: log work time against a ticket (or a project task)" gives a specific verb, resource and the two valid targets, and the API line names the exact endpoint. This is clearly distinguishable from gorelo_list_time_entries and the other read/create siblings.

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?

It states the operational constraint for invocation (any two of started_on, ended_on, actual_hours) and a clear when-not ("Do not retry after an unclear error"). It never names an alternative sibling, e.g. checking gorelo_list_time_entries to confirm whether an ambiguous submission landed, so it stops short of full routing guidance.

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