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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the destructive nature is known. The description adds valuable behavioral context beyond the annotations: the confirm:true requirement and the two-phase behavior (omitting confirm returns the entry for a final check without deleting). It also discloses the sent-invoice restriction. This is strong behavioral disclosure, though it doesn't describe the return format or side effects in detail.

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 sentences, each earning its place: the first states the sole use case, the second explains the critical confirm behavior, the third gives the sent-invoice restriction and the alternative. The most important operational detail (confirm) is front-loaded. No filler or repetition of schema content.

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 destructive two-parameter tool with no output schema, the description covers the essential context: when to use, the confirm gate, the sent-invoice restriction, and the safer alternative. It doesn't describe what the response looks like or what happens to related data, but the annotations and schema cover the safety profile and required parameter. The only minor gap is the lack of detail on the 'final check' return value, but this is not critical for correct invocation.

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 50%: entry_id has no description, while confirm has 'Must be true to actually delete.' The description compensates by explaining the confirm parameter's semantics in detail ('when omitted it returns the entry for a final check without deleting'), which is critical for correct invocation. It doesn't add meaning for entry_id, but the parameter name is self-explanatory and the required status is in 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?

The description states a specific verb ('delete') and resource ('time entry'), and explicitly distinguishes it from the sibling time.update_entry by saying 'To fix a mistake, prefer time.update_entry.' This makes the tool's purpose unmistakable and differentiates it from related tools.

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 description gives explicit when-to-use guidance: 'Use this only when the user explicitly asks to remove an entry.' It also provides a clear exclusion: 'Entries on sent invoices cannot be deleted.' And it names the alternative for fixing mistakes: 'prefer time.update_entry.' This is exactly the kind of routing an agent needs.

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