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

Beyond the sparse annotations, the description discloses important behavior: it returns id/duration/amount and explains that rate is frozen at creation time so later rate changes won't affect it. It also clarifies that rate is in MAJOR units, which is non-obvious. It does not cover every possible edge behavior, but it substantially exceeds what annotations alone provide.

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 convey the core behavior, return value, duration input options, and an important rate nuance with no wasted words. The most important usage constraint ('already worked') appears first, making the description easy to scan.

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?

Given the tool has 10 parameters and no output schema, the description covers the essential calling contract: what is created, how duration is supplied, and what the caller gets back. Optional fields and defaults are already documented in the schema, so the description doesn't need to repeat them. It is slightly short on edge-case guidance (e.g., conflicts between end and minutes, or partial project matching), but the schema covers those.

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 a baseline of 3 applies. The description adds value by explaining that the rate is expressed in MAJOR units and frozen on the entry, and by clarifying that start plus either end or minutes are the ways to specify duration. This is meaningful semantic context beyond the schema field descriptions.

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 states a specific action — 'Log time already worked as one entry' — and names the resource (time entry) plus the return payload (id, duration, amount). The phrase 'already worked' differentiates it from timer-based siblings like timer_start and timer_stop, and from mutation siblings like entry_edit/entry_delete.

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 clearly says this is for time already worked rather than active tracking, and explains the two input modes: 'start plus end or minutes'. It does not explicitly name alternatives or give exclusions, but the context ('already worked') is enough to guide an agent away from timer tools.

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