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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds useful context not in the annotations: 'credential-free' (no API key needed) and 'normalized sections' (structured, pre-processed output). It does not disclose pagination behavior or what 'sections' contain, so with annotations covering the safety profile a 3 is appropriate.

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?

A single tight sentence that front-loads the return type and resource, with a concrete example path. No wasted wording, though it is quite terse for the amount of behavior a chain-detail endpoint could exhibit.

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?

An output schema exists, so return values need not be explained, and annotations cover safety. The description is minimally adequate but does not clarify what 'sections' means or how limit/vs_currency scope the output, leaving some gaps for an agent to fill by inference.

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 all three parameters including the id format, limit default/max, and the full currency enum. The description adds no parameter detail beyond the schema, so the 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 ('Returns') and resource (normalized sections of a CoinGecko chain detail page), with a concrete URL example. This distinguishes it from the sibling coingecko_chains which lists chains rather than returning one chain's detail, though the description never names that sibling explicitly.

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?

Usage is implied by the example URL ('/en/chains/ethereum') and the requirement of a chain id, so an agent can infer this fetches detail for a single chain. However, there is no explicit when-to-use vs sibling (e.g., coingecko_chains) guidance and no exclusions or prerequisites beyond 'credential-free'.

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