Update Work Item Fields

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

There are no annotations provided, so the description carries the full burden. It discloses that this is a mutation operation (updates via REST), that json-patch is assembled server-side and restricted to /fields/*, and that historyComment persists to System.History. This is meaningful behavioral disclosure. Minor gaps: no mention of API version, auth requirements, or what the response looks like, but the core mutation semantics and server-side patch assembly are transparently stated.

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?

The description is a single dense paragraph that covers purpose, field format, historyComment behavior, the at-least-one constraint, and the default organization. Every clause serves a purpose and there's no filler. It loses the full 5 only because it's slightly packed/undifferentiated as one long sentence flow rather than clearly front-loaded with the most critical info first, but it is still efficient with zero waste.

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 straightforward mutation tool with 3 parameters and full schema coverage, the description covers the essentials: field format, historyComment behavior, validation constraint, and default organization. No output schema exists, so describing the return format would be desirable but is a minor gap. Overall it's adequate-to-strong for a filtered mutation tool, though it could mention what the response contains and permission requirements.

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 the schema already documents all three parameters. The description adds value beyond this by explaining the field key format ({System.State: 'Resolved'}), that a historyComment writes to System.History, and that at least one of fields/historyComment is required. This enriches the otherwise generic schema descriptions. Would be a 5 if it added more depth on value validation or response behavior.

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?

Description clearly states verb+resource (updates work item fields via REST API) and specifies the field reference-name format with an example. It differentiates from siblings by noting it updates only /fields/* and that fields and historyComment are required-or-one. However, it doesn't explicitly contrast with sibling tools like az_workitem_attach or az_workitem_relations, so it loses the full 5 which requires explicit sibling distinction.

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 description gives clear usage context: how to specify fields using reference names, that a historyComment writes to System.History (Discussion), and the constraint that at least one of fields/historyComment must be provided. It also states the default organization. However, it does not explicitly say when NOT to use this tool or name alternative siblings for other work item operations (attach, relations), so it misses the exclusions that would earn a 5.

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