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

With no annotations, the description carries the burden and does well: it discloses the return fields, the cost model ($0.007 per search, pass-through with no markup, read from a payment challenge on every call), and the downstream tool. It omits auth requirements, rate limits, and pagination behavior, keeping it short of a 5.

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?

Front-loaded with purpose, then return shape, then the follow-up route, then cost. Every sentence carries information, though the final pricing clause is dense and slightly overlong relative to its value.

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?

For a six-parameter search tool with no output schema, the description supplies purpose, return fields, cost, and the hand-off to web_scrape_batch. Parameters are fully covered by the schema, so the only real gap is auth/rate-limit context.

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 every parameter (limit, query, since, domains, snippets, excludeDomains) is already documented in the schema with defaults and constraints. The description adds no parameter-level detail beyond the query-vs-url framing, which is the expected baseline when the schema does the work.

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 ('Search the web with Exa's index') and immediately distinguishes itself from URL-based siblings with 'a query instead of a url'. The return shape (title, url, snippet) is named, so an agent knows exactly what this produces.

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 an explicit use condition ('for when you do not know where to look') and names the correct alternative and follow-up path ('pass the urls to web_scrape_batch'). The division of labor between search and scrape is unambiguous.

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