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

Annotations already declare readOnlyHint=false, destructiveHint=true and openWorldHint=false, so the safety profile is structured rather than described. The description adds nothing about mutation semantics — notably it never explains why a create is flagged destructive (e.g. behavior when the id already exists) or that subsequent add_field calls are the intended follow-up. It does not contradict the annotations, but it leaves the surprising destructive flag unexplained.

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 sentences, zero filler, with the core action front-loaded before the disambiguation clause. Every clause carries information an agent needs for selection.

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 create tool with a fully documented schema, annotations carrying the safety flags, and no output schema, the description covers identity and one routing decision. The remaining gap is sibling coverage: add_entity_with_fields is the obvious shortcut an agent might miss, and no guidance is given on when a single add_entity beats that combined call.

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% across 11 parameters, with per-parameter text covering auto-placement for x/y, kebab-case ids, color defaults, and the replace-vs-clear semantics of kindMetadata, so the schema does the heavy lifting. The description contributes only the 'kind=entity' framing and the 'ready to receive typed fields' hint, adding little beyond the structured fields — baseline 3.

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 ('Creates an ERD entity') and pins the implementation detail ('block with kind="entity"'), then adds what it is for ('ready to receive typed fields'). It explicitly distinguishes itself from the sibling add_cell by contrasting data-table modeling with org-chart blocks.

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?

'Fits when modeling a data table; an org-chart block belongs to add_cell' gives an explicit when-to-use plus one named alternative, which is strong. It never mentions add_entity_with_fields, the near-duplicate sibling that creates an entity plus its fields in one call — the single most consequential alternative left to inference.

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