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

Annotations already declare destructiveHint=true, idempotentHint=true, readOnlyHint=false, so the safety profile is covered; the description then adds real value beyond that: the exact legal status pipeline, error codes ILLEGAL_TRANSITION and DATE_ORDER, day-grain date handling with null-clears semantics, and that priority merges into artifact metadata rather than replacing it. It stops short of saying whether omitted fields are left unchanged or naming required permissions.

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?

Four dense sentences that are front-loaded with the field list and then layer constraint after constraint; no filler, no restatement of the title, and every clause carries either a format rule or an error contract.

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 7-parameter mutation tool with no output schema, the description covers the mutation surface, the validation contract, and the metadata-merge quirk. The remaining gap is the shape of the success response and confirmation of partial-update semantics for unspecified fields.

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 43%, so the description has to carry weight and largely does: it names all six optional fields, explains status enum progression, spells out the date format (YYYY-MM-DD or ISO), the null-clears behavior, and the start ≤ target constraint. It adds little on title/content length limits (left to schema) and never mentions epicId explicitly, so not 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?

Specific verb ('Update') plus resource ('an epic') plus an explicit enumeration of the six updatable fields. It is clearly distinguishable from create_epic/delete_epic by the resource, but it never differentiates itself from update_story or bulk_update_stories, so the sibling-routing job is left to the name alone.

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 status-transition rule (DRAFT → PUBLISHED → ARCHIVED) and the date validation imply when the call will fail, which is useful context for choosing it. However, there is no explicit statement of when to use this versus update_story, bulk_update_stories, or transition_sprint, and no prerequisites/permission guidance.

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