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

Goes well beyond the readOnly/destructive/idempotent/openWorld annotations by disclosing that values are provisional and may change, that data is OGL-licensed, that units are retained (hydrological units normalised to SI), and concrete rate limits (60/hour, 300/day, anonymous fallback after monthly quota). Auth requirements (no API key needed) are also stated.

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 critical constraints (cap, window) are front-loaded, but the passage is long and includes filler such as 'TerraMCP is a Wrench AI service', which does not help an agent call the tool. Rate-limit and licence details earn their place; the branding sentence does not.

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 it partially does so ('Returns source data and provenance', 'values retain upstream units and timestamps'). Combined with the licence, volatility, and rate-limit notes, an agent has enough to call it correctly, though the exact response shape remains vague.

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 series_id, start, end, and limit. The description's 'up to 1,000' and 'at most 7 days' merely restate schema constraints, adding no new syntactic or format detail beyond the schema.

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 (Get), resource (SEPA KiWIS observations), and scope (up to 1,000 values by series_id over at most 7 days). The 'by series_id' framing implicitly separates it from sepa_series (identifiers) and sepa_stations, so an agent can distinguish 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?

The 7-day window and series_id requirement imply the use case (fetch observations for a known series over a short window), and the schema points to sepa_series as the source of IDs. However, there is no explicit when-to-use/when-not guidance and no alternative named in the description text itself.

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