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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false, openWorldHint). The description adds genuine behavioral context beyond that: the anti-fabrication note that tide times come only from this call's output, the one-call-per-location/day-range rule, and the argument-mode requirement. It stops short of describing output format or latency, so not a 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?

The core purpose is front-loaded in the first sentence, followed by clearly labeled sections. It is dense with many query examples, which is slightly verbose, but each block (routing, required args, chain, anti-fab) earns its place.

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 return-value burden and partially addresses it via the anti-fabrication caveat that tide times appear only in the output. For a read-only tool with 100% schema coverage and thorough usage guidance, this is nearly complete, though an explicit return-shape hint would raise it further.

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 the schema already documents all six parameters including the lat/lon pairing and the lat+lon-only constraint on date_start/date_end/station_limit. The description reinforces the either/or argument logic and gives city examples, but adds little 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+resource (retrieving low/high tide times for a coastal location) and explicitly distinguishes itself from siblings like get_current_weather, resolve_location, and a routing server. An agent can immediately tell what this tool returns and what it does not.

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?

It provides explicit 'When to use' triggers with concrete DE/EN example queries, a 'When NOT to use' section naming the correct alternative tool for each excluded case, plus a typical chain and multi-call guidance. This is a textbook routing-oriented usage block.

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