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

Annotations only cover the safety profile (readOnlyHint=false, destructiveHint=false). The description adds real value beyond that: it declares partial-update behavior ("Only fields supplied are changed"), the prerequisite option lookups, and the token-scope requirement. It does not disclose the destructive facility-replacement semantics, but that is carried in the schema, and nothing here contradicts the annotations.

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?

Three tight sentences with no filler. Purpose and partial-update behavior are front-loaded, then prerequisites, then auth — each sentence earns its place.

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 mutation tool with no output schema and 45% param coverage, the description covers the essentials: what changes, how to source valid FK values, and the auth requirement. The main gap is that it does not flag the full-replacement nature of roomFacilityFk, though the schema does.

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 coverage is low (45%), so the description should compensate. It points to the source tools for roomTypeFK/roomFacilityFk (which the schema also states) but says nothing about beds, maxPerson, roomTitle, mainBedSize, otherBedSize, or roomDescription. It adds workflow context but leaves several parameters undocumented, so it only partially compensates.

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 ("Update an existing room on a Stay") and the partial-update semantics, which lets an agent separate it from createStayRoom and deleteStayRoom. It stops short of explicitly naming those siblings, but the verb makes the distinction clear.

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?

Gives a concrete prerequisite workflow (call getRoomTypeOptions(stayId) and getRoomFacilityOptions() before setting roomTypeFK/roomFacilityFk) and the auth context (MCP agent token scoped to owning account). No explicit when-not or exclusion conditions are stated, so it lands at clear-context rather than full routing guidance.

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