Update Surface Element

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

Goes well beyond the annotations by disclosing two non-obvious behaviors: geometry fields merge with existing xywh while text/label/title clobber the underlying Y.Text wholesale, and mismatched fields are silently reported instead of rejected. That is genuine mutation-context information an agent cannot get from readOnlyHint=false or destructiveHint=false. Missing are error/conflict behavior and any hint about why idempotentHint is false for these merge semantics.

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: identity and operation first, then the merge rule, then the replace rule, then the failure-ish case. Zero redundancy and nothing buried at the end that should be up front.

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 31-parameter mutation tool with full schema coverage, full annotations, and an output schema, the description supplies exactly the missing layer — the semantics of combining fields — and even references the 'ignored' response field. Nothing essential to invoking it correctly is absent.

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 100% across 31 parameters, so the per-field documentation is already carried by the schema; the description earns extra credit by explaining the interaction between x/y/width/height and the current geometry, which no individual parameter description states. It does not, however, group or prioritize the type-scoped families (shape vs connector vs group) beyond one sentence.

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 ("Partially update a surface element by id") and pins down the partial-update contract immediately, which cleanly separates it from add_surface_element, delete_surface_element and list_surface_elements. An agent knows exactly what class of operation this is without opening the schema.

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 when to use this over a full write by describing the merge-vs-replace rule ("move without resizing, or vice versa") and warns that type-inapplicable fields land in the 'ignored' list rather than erroring. It does not explicitly name a sibling alternative or state prerequisites such as needing an existing elementId, so it falls short of 5.

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