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

Annotations already declare readOnly, idempotent, non-destructive and non-open-world, so the safety profile is covered; the description adds genuine context beyond that by enumerating return contents (names, descriptions, endpoints, agent card URLs, skills/tools, automated check score). It does not mention result caps, pagination limits, or why the "check score" should be trusted, which keeps 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 the usage condition and then the resource scope, then the return summary — a sensible order with little waste. "Browse at /agents" is a mild non-actionable addition for an agent, but it costs only one clause.

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 steps in to describe the shape of results, which is the main gap a caller would otherwise face. Remaining gaps are pagination behaviour and filter-combination semantics for a 6-parameter, all-optional search — noticeable but minor for a read-only directory lookup.

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 100%, so all six parameters are already documented, including the protocol and category enums. The description mostly restates those facets and adds no syntax or combination logic (e.g. whether q plus category AND together, or how page interacts with result counts), so 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 (search) and a clearly scoped resource (the Rooms agent directory of MCP servers, A2A agents and x402 paid APIs), and names the filterable facets. No sibling tool in the list performs directory search, so an agent can tell this apart immediately without opening the schema.

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 when you need an agent or tool you don't have" is an explicit triggering condition, which is exactly the decision point for this tool. It does not name exclusions or alternatives, but the sibling set (message_agent, open_job, list_rooms, etc.) is functionally distinct, so there is little ambiguity left.

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