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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the safety profile is covered. The description adds that this is a correction/enrichment of an existing record rather than a creation, which is useful context. However, it does not disclose partial-update semantics (what happens to fields omitted from the call), permission requirements, or whether changes are reversible or audited.

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 tight sentences plus a reference URL. The purpose is front-loaded, the alternative-tool guidance follows immediately, and no sentence is redundant.

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 9-parameter mutation tool with no output schema and only 22% schema coverage, the description should clarify the required event_id and the partial-vs-full update contract. It covers the field list well but leaves those two gaps, making it adequate rather than complete.

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 only 22% across 9 parameters, so the description must carry more weight. It names title, description, category, dates, impact and link, mapping to roughly six params, but omits the required identifier event_id and the task_id linkage entirely, leaving the most important parameter undocumented in prose.

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 ("Correct or enrich a project timeline event") and enumerates the mutable fields, so an agent immediately knows this is an edit operation on an existing event. It alludes to the log_project_event sibling by warning against "logging a duplicate event," but never names that sibling explicitly, so the differentiation is implied rather than stated.

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?

"Use this instead of logging a duplicate event when the facts change" gives an explicit trigger condition and a named alternative behavior, which is strong routing guidance. It does not cover when-not-to-use (e.g., correcting a non-existent event, or when the event should instead be deleted/archived).

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