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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds that output is normalised to SI units with source provenance and covers all station measures, plus an 'authenticated' hint, but it omits pagination/rate-limit behaviour and gives no hint about what idempotentHint=false means for repeated calls.

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 short sentences with the routing rule placed last, so the core capability is front-loaded. The only waste is the name-restating 'TerraMCP authenticated router: flood_get_readings' prefix.

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 does partially cover return content (normalised SI data, source provenance), which helps. However, for a 2-parameter tool with zero schema description coverage it says nothing about the inputs, leaving an agent to infer required station_id format and latest_n semantics from the raw schema alone.

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 0% and the description never mentions either parameter. station_id (required) and latest_n (count, default 1, max 100) are left entirely to the raw schema, so the description does not compensate for the documentation gap.

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 ('Returns normalised SI data and source provenance') and clarifies scope ('Returns all station measures'), which separates it from the rainfall-only sibling. The leading 'TerraMCP authenticated router: flood_get_readings' is boilerplate that adds no distinguishing information, but the substantive sentence is clear.

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?

Explicitly names an alternative and the condition that selects it: 'use rainfall_latest for rainfall only', implying this tool is for the broader/all-measure case. It gives no exclusions beyond that single routing rule and no prerequisites (e.g., how to obtain a valid station_id).

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