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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds real behavioral value beyond that: it discloses the return shape (per-data-centre rows plus dataselect and station service URLs) and draws the boundary that waveform bytes come from the returned URL, not this tool.

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 example question front-loads the intent, and the following sentences each carry substance (what it returns, and the boundary against byte-fetching). The long em-dash sentence is dense but not padded.

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?

Seven optional params are fully described in the schema and there is no output schema, so the description appropriately focuses on intent and return contents. It covers enough for correct invocation, though it could note federated-catalogue latency or per-data-centre variability when querying many centres.

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%, with each of the 7 optional parameters documented (defaults, wildcards, formats), so the schema carries the load. The description only refers generically to a 'network/station/channel/time window' and adds no syntax or default detail beyond what the schema already provides; baseline 3 applies.

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: it finds which FDSN data centres hold seismic waveform data for a network/station/channel/time window, sourced from the EarthScope federated catalogue. It cleanly separates itself from the act of downloading bytes, but never names the closely related siblings fdsn_stations and fdsn_events, so sibling differentiation is only partial.

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?

Frames the use case as the 'is the data there, and from whom' question and supplies a concrete example query, which is strong contextual guidance. It also implicitly excludes byte-fetching. It stops short of explicitly telling the agent when to reach for fdsn_stations or fdsn_events instead.

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