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

Annotations already declare destruction, idempotency and open-world scope, so the bar is lower. The description still adds real value by disclosing partial-update semantics ('only the fields you pass change; the previous values are overwritten'), which an agent needs to avoid accidentally clobbering data. It stops short of noting permissions or irreversibility of the billed flag.

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 sentences, zero padding, and the most decision-relevant token ('WRITE') is front-loaded followed immediately by the scope and endpoint. Everything earns its place, though the endpoint string is somewhat redundant for an agent that never sees URLs.

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 partial-update mutation with full schema coverage and annotations carrying the safety profile, the description supplies the one thing the structured fields lack: that omitted fields are preserved while passed fields are replaced. No output schema exists, so return values need not be explained. Minor gaps (auth requirements, conflict behavior) are acceptable here.

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 schema fully documents each field's type, bounds and format. The description only restates the same field names (hours, notes, date, task, billed) without adding format or constraint detail beyond the schema, so the baseline of 3 is appropriate.

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 description gives a specific verb ('change'), an explicit resource ('an existing time entry'), the endpoint, and the exact set of updatable fields. It cleanly separates this from tick_create_entry and the tick_get_* read tools, so an agent can select it without opening the schema.

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?

The 'WRITE:' prefix and 'change an existing time entry' imply usage context, and the field list tells the agent what can be modified. However, it never states prerequisites (e.g. needing the entry_id from a list/get call) or when to prefer this over other write tools, so guidance remains implied rather than explicit.

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