Add a Circle Annotation

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

Annotations already declare it is a non-read-only but non-destructive write, and the description goes beyond them by stating it returns the circle's id and that get_annotations reports circles as kind "ellipse" — a non-obvious lookup detail. It says nothing about persistence with the saved file or z-order/layering.

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?

Purpose, return value and quirk are front-loaded in two tight sentences; the example bullets are useful but slightly padded as a second list for a tool whose usage is already evident.

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?

With an output schema present, the description need not explain return shape, yet it helpfully names the id return anyway. Adequate for a simple 4-param shape tool; only layering/persistence behavior is left unstated.

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?

All four parameters already carry descriptions, patterns, ranges and defaults in the schema, so a baseline of 3 applies. The description adds only that coordinates are in the same logical-workspace space it draws on, nothing on radius/color semantics.

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?

Specific verb ('Draw') plus resource ('a circle on the logical workspace'), with concrete domain purposes (group a LAN, broadcast/collision domain, OSPF area) that separate it from add_line_annotation and add_text_note.

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?

Example intents ("Circle the devices in VLAN 10", "Mark each broadcast domain") make the intended situations clear, but there is no explicit when-not guidance or named alternative for a non-circular grouping.

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