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

Annotations only give the generic mutation/open-world profile; the description adds the non-obvious behavioral contract: the first unpaid call returns an isError holding an x402 PaymentRequired object, payment goes in _meta["x402/payment"], settlement returns in _meta["x402/payment-response"], and nothing is charged on failure. That is exactly the context an agent cannot get from structured fields.

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 and usage, then input, then payment mechanics, then a discovery pointer — a sensible order. It is slightly long, and "Give the server's URL" restates the required schema field, but each payment sentence carries necessary 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?

With no output schema, the description still covers return values (tools plus flagged descriptions) and the full paid-call handshake. Nothing an agent needs to invoke this correctly on the first or second attempt 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?

The single `url` parameter is already documented at 100% schema coverage, including the https-only pattern and Streamable HTTP endpoint meaning. The description's "Give the server's URL" adds no semantics beyond the schema, so the baseline 3 applies.

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: it connects to an MCP server, lists its tools, and screens each description for hidden agent instructions. That is clearly distinguishable from siblings like screen_text (screens arbitrary text) and check_x402_endpoint (probes payment terms), and it names list_agoreum_tools as the discovery path.

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?

"Use it before connecting your agent to an MCP server you do not control" gives an explicit trigger condition, and list_agoreum_tools is named for the broader catalog. There is no explicit when-not or a direct pointer to screen_text for non-MCP text, so it stops short of the full 5.

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