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

Annotations declare destructiveHint=true and readOnlyHint=false; the description corroborates the destructive nature by explaining that null clears the estimate, which is non-obvious. It also adds the authorization requirement and the 10,000-hour cap. It doesn't say whether the previous estimate is overwritten or how failures surface, so not a full 5.

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 dense sentences with the core action front-loaded, followed by format rules and the permission note. The example formats are compact and each served a distinct parsing case rather than padding.

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 2-parameter mutation tool with no output schema, the description covers format, bounds, clearing, and authorization — essentially everything needed to invoke it correctly. Minor gap: it doesn't clarify overwrite semantics or interaction with estimate-adjacent siblings.

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?

With only 50% schema description coverage, the description must compensate, and it does: it defines the unit syntax (4h, 1h30, 90m, 1.5h), clarifies that a bare number means minutes, and documents the null-clearing behavior. cardId remains undocumented in both places, keeping it from a 5.

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 ('Sets how long a task is expected to take') plus the full lifecycle including clearing. An agent can distinguish this from siblings like set_task_field, convert_estimate_to_invoice, or update_task without opening either 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?

Clearly indicates the two usage modes (set a duration, or clear it with null) and states the prerequisite ('Needs the editor role on the project'). It does not name explicit alternatives or exclusions (e.g., when to prefer set_task_field), 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.