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

With no annotations, the description carries the full burden and does so well: free of charge, no website needed, bearer required but no verification needed to price, the rail surcharge is rolled into joules_all_in, and graph paths refund unused hops. These are non-obvious behavioral facts an agent could not infer otherwise.

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?

It front-loads the value proposition ('exact per-caller price ... BEFORE you make it') and every clause carries information, including the relay endpoint. It is dense and slightly example-heavy, but nothing is truly wasteful.

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 still names the fields the agent must read (joules_all_in, joules, rail_fee_joules, refund_on_empty, quote_is_maximum) and explains what each means relative to funding the call. Nothing needed to call and interpret this tool is missing.

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 0%, so the description must compensate, and it does: `path` is explained as the API path the call would hit with concrete examples, and `hops` is defined as graph depth (1-20) applicable only to relationships paths. This directly supplies meaning absent from the bare 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 precise verb and resource: it returns the exact per-caller price of a metered call before the call is made. It also disambiguates itself from the sibling tools by mapping example API paths to their corresponding tools (relationships, look_from, map_viewport, company, nearby).

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 description clearly frames the correct moment to use it ('BEFORE you make it') and shows how to derive the `path` argument from the tool you intend to call, which is actionable context. It stops short of an explicit when-not/alternative clause, so it's a strong 4 rather than a 5.

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