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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety/open-world profile is covered structurally. The description adds the pagination ceiling ('up to 100 rows') but that duplicates the schema's limit constraint, and it says nothing about rate limits, response shape, or data freshness.

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 sentences, zero padding; the core action leads, then required-input sourcing, then sibling disambiguation. Every sentence carries actionable information.

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 described. With annotations covering safety and the schema covering all four parameters at full coverage, the description completes the picture an agent needs to invoke this correctly.

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 baseline is 3, but the description adds genuine meaning: it tells the agent where the required slug comes from and what vs_currency controls (quotes), going beyond the terse schema descriptions.

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 ('Fetch paginated coin rows from a CoinGecko public category page') with scope (paginated, up to 100 rows). Explicitly distinguishes itself from coingecko_markets (broad market table) and coingecko_coin (single asset), so an agent can route correctly without opening schemas.

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?

Gives explicit prerequisites ('Get slug from coingecko_categories'), tells the agent what vs_currency is for, and names the two alternative tools with the conditions that select them. Both when-to-use-this and when-not are covered.

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