mcp_agents_list

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: unreachable agents are still returned (online=false), the LAN is auto-scanned hourly with last_updated_at as the timestamp, and rescan forces a slow synchronous sweep. It also flags the security implication of has_default_key.

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-loads the core purpose and return fields, then layers on rescan guidance and the security instruction. Every sentence is load-bearing, though the security-warning directive is slightly tangential to invoking the tool.

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?

No output schema exists, yet the description fully documents return fields and their semantics (online via live /hello probe, type pi/pico, etc.), and covers the single param, caching cadence, and cost. Nothing an agent needs to call it correctly 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% (the boolean 'rescan' has no schema description), so the description must compensate, and it does: it explains what rescan=true does, its performance cost, and the condition under which it should be used. This is meaning well beyond the bare boolean type.

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 ('List configured agents (Pi or Pico)') and immediately enumerates the returned fields. An agent can distinguish it from siblings like mcp_agent_restart, mcp_agent_upgrade, and mcp_agent_logs without opening any 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?

Explicitly states when to use the rescan parameter and, crucially, when NOT to ('avoid doing this unless the user explicitly asks to find new hardware'), citing the slow scan cost as the reason. It also prescribes a follow-up action (warn the user about has_default_key).

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