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

Annotations already declare read-only/open-world behavior; the description adds that results are ranked, grouped, live, and include a recommended NEXT MOVE, and that re-calling is the way to get updates. This is helpful context, though it does not go into rate limits, auth, or staleness, so it stops 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?

The main purpose is front-loaded, followed by input guidance, return behavior, update policy, and examples. Every sentence contributes distinct information, including the external webhook alternative, without fluff.

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 two-parameter read-only tool with an output schema, the description covers how to invoke, what to expect, and how to refresh results. However, since sibling list_markets exists and the markets parameter accepts arbitrary codes, an explicit pointer to list_markets for available codes would have made the workflow fully discoverable.

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. The description adds value above the schema with natural-language usage ('Pass a short description of what the business sells or does'), concrete market code examples, and two JSON examples showing valid combinations.

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?

Opens with a specific verb and resource: 'Find live public tenders, grants, RFPs and buyers for any business, by country/market.' This clearly identifies what the tool does and, by focusing on opportunity discovery rather than market metadata, distinguishes it from the sibling list_markets tool without needing to name it.

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 direct invocation guidance: pass a short business description and optionally market codes. It explicitly handles update behavior ('call this tool again for the latest answer') and names the alternative (POST to the subscribe endpoint) with the condition that distinguishes backend apps from conversational agents.

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