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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and open-world behavior are covered. The description adds one useful non-duplicated trait — 'costs the same as that API' — but says nothing about required credentials, rate limits, error behavior, or how the free-form params are applied, which matters for an open-ended proxy 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?

A single tight sentence with the purpose and provider scope front-loaded, plus a parenthetical pointer to listCapabilities. No filler; the only slight drag is the cost clause tacked on at the end.

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?

As an open-ended passthrough to four external APIs with no output schema and undocumented parameters, the description covers routing well but is thin on parameter mechanics, auth expectations, and result shape. It is adequate to start but not fully sufficient for confident invocation.

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% across 3 params, so the description must carry the load. It conveys the provider+endpoint mental model ('by path') and echoes the four provider options, but the nested free-form 'params' object — the most ambiguous parameter — is left completely unexplained, so it only partially compensates.

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 (Call) and resource (any Google/Instagram/TikTok/Amazon endpoint by path) and explicitly positions itself against siblings: it exists for 'the few the other tools do not cover.' An agent can tell instantly why it would pick providerRequest over amazonSearch or tiktokVideo.

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 a clear selection rule (only endpoints the other tools do not cover) and points to listCapabilities as the discovery mechanism for those endpoints. The exclusion is implied rather than spelled out per-provider, but the routing guidance is genuinely actionable.

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