List devices

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is largely covered; the description still adds real value by disclosing that discovery performs a local-network scan and 'connects none of them', i.e. the call is a candidate-producing probe, not a mutation. Minor tension: a LAN scan (mDNS/port 5555) sits awkwardly beside openWorldHint=false, though the description's explicit no-connect guarantee keeps the agent from misreading it as an external write.

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 core purpose and the 'Start here' routing cue, with the discover fallback second. The final sentence is long and stacks three clauses ('any time and as often as needed, and connects none of them'), which could be trimmed, but every sentence carries 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?

No output schema exists, so the description carries the return-format burden and does so: device serial/state/description, remembered-but-disconnected addresses, and candidate lists from discovery. Combined with 100% parameter coverage and complete annotations, an agent has everything needed to call it and to interpret the result.

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 the baseline is 3, but the description goes beyond the schema by supplying the trigger condition for discover=true (the target device is absent from the list) and the repetition allowance ('any time and as often as needed'). It doesn't restate the ~10 s timing, which lives in the schema, but the added decision context is genuine.

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 connected Android devices') plus the exact fields returned (serial, state, description) and mirrors the underlying command (adb devices -l). It also covers the secondary result set (remembered but disconnected addresses), so an agent can distinguish it from adb_connect/adb_pair without reading a 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 positions itself as the entry point ('Start here: the other tools take serial from this list') and gives a concrete escalation rule ('If the device the user means is not in the list, call again with discover=true'). It also bounds the discover call: 'any time and as often as needed, and connects none of them.' This is when-to-use, when-to-escalate, and a stated non-side-effect in three sentences.

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