Add Surface Element

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

Annotations already declare readOnly=false, destructive=false, idempotent=false, so safety is covered; the description adds a genuinely non-obvious behavioral fact: inapplicable style fields are echoed back in a response 'ignored' list. It stops short of noting that the operation is non-idempotent (repeated calls create duplicates) or what permissions/docId scope are needed.

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?

Four short sentences, front-loaded with the core action, then element capabilities, use case, and the ignored-field caveat. No filler, though the parenthetical '(mirrors update_surface_element)' is slightly cryptic without direct routing language.

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?

The tool has 31 parameters and an output schema; the description defers parameter specifics to the (fully documented) schema and to the output schema for the 'ignored' list, which is appropriate. Missing is any note that this is a non-idempotent create (duplicate calls duplicate elements) or how docId/workspaceId must line up.

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%, so baseline is 3; the description earns one more by explaining connector binding semantics ('draw arrows between shapes (by id) or between absolute points') and which style families apply per element type, which reinforces how sourceId/targetId vs sourcePosition/targetPosition are chosen.

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?

Names a specific verb and resource ('Add a shape, connector, text, or group to the AFFiNE edgeless canvas surface') and enumerates the element kinds, so an agent immediately knows the scope. It also implicitly separates itself from update_surface_element by noting the 'ignored' report 'mirrors update_surface_element'.

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?

'Use for building diagrams programmatically' gives a context cue, but there is no explicit when-not guidance or directive such as 'to modify an existing element use update_surface_element' / 'to inspect use list_surface_elements'. The routing to siblings is left to be inferred from the mention of the mirror behavior.

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