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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds value by disclosing that the result includes both system and custom fields, which tells the agent the listing is exhaustive rather than filtered, though it says nothing about pagination or field metadata shape.

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 short sentences with zero padding: the first states what is returned, the second states why to call it. Nothing redundant and nothing buried.

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 simple, read-only, single-optional-param tool this is nearly sufficient; the scope of fields covered is stated. Since there is no output schema, a brief note on what each field entry contains (id, name, type) would have made it fully 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?

Only one optional parameter, and the schema documents the account-selection behavior at 100% coverage, so the schema carries the load. The description adds nothing about the account parameter, matching the baseline 3 for high schema coverage.

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 ('List all available Jira fields') and clarifies scope ('both system and custom'). No sibling tool lists Jira fields, so it is unambiguously distinguishable from jira_get_issue, jira_search, and the rest.

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?

Explains the purpose context: discovering field IDs needed for creating or updating issues, which implicitly routes the agent to jira_create_issue/jira_update_issue after calling this. It gives a clear when-to-use but no explicit exclusions or named alternatives.

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