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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, but the description adds genuinely non-structured context: the required permission (project.content.create), the 'null to clear' behavior that explains the destructive nature for the description field, and the dated deprecation window for the name alias. It still does not spell out any other consequence of the destructive hint, so not a 5.

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 paragraph that front-loads the action and semantics, then enumerates fields. Every clause (length bounds, null-clearing, hex format, slot semantics, permission) carries operational information, so there is no padding.

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?

With no output schema, the description only needs to cover invocation, and it does: all six parameters are addressed, permissions are stated, and the deprecation timeline is given. The one remaining gap is that destructiveHint=true is not fully justified beyond null-clearing, so it is not fully exhaustive.

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 100%, so a 3 is the baseline; the description earns above that by explaining merge semantics and by glossing 'order' as an explicit slot in the project's epic order, which adds meaning beyond the schema's bare 'Non-negative integer'. It mostly restates the length/format constraints already 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?

States a specific verb (partially update) and resource (one Epic), with 'partially' signaling PATCH semantics. Among the many sibling update_* tools, the resource noun makes it unmistakable versus update_task, update_issue, or update_sprint, and it is clearly distinct from create_epic/get_epic.

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?

'Pass only the fields you want to change' explicitly frames this as a merge-style PATCH and tells the caller how to invoke it. It does not name adjacent alternatives (e.g., move_task_to_epic, create_epic) or state when not to use it, so it falls just short of full routing guidance.

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