set_default_source

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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the agent knows this is a non-destructive local state change. The description adds nothing further — it doesn't say whether the change persists across sessions, whether it requires PulseAudio/PipeWire, or what happens if the name doesn't match.

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?

One short sentence with the key distinguishing word ('input') front and center; nothing redundant or padding.

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 one-parameter, non-destructive setter with a fully documented schema and no output schema, the description covers the essentials. Minor gaps remain around discovering valid sources and failure behavior, but nothing critical 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 description coverage is 100% and the single 'source' parameter is documented as 'Source name or numeric ID', which the description only echoes. Baseline 3 applies since the schema carries the parameter meaning.

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?

Specific verb (Set) plus resource (default audio input device), with the 'input' qualifier distinguishing it from the sibling set_default_sink which handles output. It never names that sibling directly, but an agent can infer the split from resource wording alone.

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?

The phrase 'default audio input device' implies the use case (microphone selection) and implicitly contrasts with the sink counterpart, but there is no explicit when-to-use statement, no prerequisite (e.g. the source must appear in list_audio_sources), and no error guidance for an unknown name.

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