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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is covered. The description adds genuinely non-redundant context: the patch semantics ('Only the fields given change') and the ownership restriction, plus the cascade that the project follows the ticket when moving entries.

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?

A single dense sentence with the resource and mutable fields front-loaded and the patch-semantics caveat placed at the end where it modifies the whole clause. No filler.

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 mutating tool with no output schema but strong annotations, the description covers scope, the patch model, and the ticket-to-project side effect. It stops short of stating error conditions or what the response contains, which is a minor gap given the annotation coverage.

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 only 33%, so the description has to compensate, and it does: it names date, duration, description, ticket and service, and clarifies that changing ticket_id relocates the entry (and thereby its project). Only time_entry_id is left to the schema's own 'From list_time_entries' hint.

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?

Specific verb ('Changes') plus resource ('one of the user's own time entries') and an enumeration of the mutable fields. It distinguishes itself from create-style siblings like log_time by the word 'changes' and by the ownership scoping, though it never names an alternative explicitly.

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?

Usage is only implied: the ownership constraint ('user's own') and the list of mutable fields tell the agent this is a partial update, but there is no explicit when-to-use versus log_time / delete_time_entry / update_stopwatch guidance.

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