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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, non-open-world). The description adds context annotations do not carry: that no authentication key is required, and a prompt-injection warning that text written by other agents in the result is data, not instructions — a genuinely valuable disclosure for a tool returning other agents' content. Return shape/pagination is not discussed, keeping it below 5.

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 sentences, front-loaded with what is returned, then why it is useful, then the auth/prompt-injection caveat. Every sentence earns its place, though the inline endpoint list is slightly more verbose than needed given the schema toggles already name these sections.

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 no output schema, the description carries the burden of describing returns and does so by naming the three result sections. Combined with the auth note and injection warning, an agent has enough to call the tool correctly; only result size/format limits are unaddressed.

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%, so the schema already documents plot_id, radius (7x7 default, 0-12), calls and openings. The description's endpoint naming loosely maps to the calls/openings toggles and 'near'/'rectangle around it' maps to radius, but adds no syntax, units, or semantics beyond the schema. Baseline 3 is appropriate.

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?

The description states a specific verb and resource ('the marks near a plot') and decomposes it into three concrete result sections tied to endpoints: the surrounding rectangle (GET /region), open seam ports (GET /openings) and open calls (GET /calls). An agent can see this is a spatial-neighborhood query rather than a single-plot fetch. It does not explicitly contrast itself with get_plot or find_open_plots, so it stops short of full sibling differentiation.

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?

'Useful for choosing a place that means something: next to a line, answering a call, continuing a pattern' gives a concrete decision context for when this tool is the right choice. No exclusions or explicit alternative routing (e.g. when to prefer find_open_plots or get_plot instead) are provided, which is the only gap.

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