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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description adds rich context beyond them: cost magnitude (1728 rays, 18 topography calls), a shared public quota, per-day caps, serialisation, de-duplication, and instant free cache hits. This is exactly the behavioral disclosure an agent needs before invoking an expensive shared-resource operation.

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?

Front-loads what the tool does, then the cost/limit warning, then the cache note. Every sentence carries operational information — quota, alternatives, refusal semantics — with no filler, despite the length.

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 still enumerates the return payload (per-direction protection, swell blocking, hourly comfort, depth, seabed nature), and for a 2-parameter tool it covers cost, caching, limits, and alternatives. An agent has everything needed to decide and invoke correctly.

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 0% and neither latitude nor longitude is described in the schema, but the description implies the coordinate pair targets one precise anchorage. Beyond confirming single-point semantics, it adds no format, range, or precision guidance. Given only two self-evident coordinate parameters, this is adequate but not additive.

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+resource ('directional shelter analysis of ONE precise anchorage') and enumerates concrete outputs: per-direction wind protection, swell blockage, hourly comfort over three days, depth, seabed nature. It explicitly contrasts its single-spot scope against the coastline-sweeping behavior an agent might otherwise assume, separating it from siblings.

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?

Explicit when-to-use ('a SINGLE spot the user has in mind'), explicit when-not-to-use ('Do NOT call it repeatedly to sweep a coastline'), and it names the correct alternative tool (`find_known_anchorages`) plus a non-tool route (the app). It even pre-explains that a refusal is a budget limit rather than an error, which prevents misdiagnosis.

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