ble_write_descriptor

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

No annotations are provided, so the description must disclose behavioral traits. It mentions the environment variable requirement but does not elaborate on side effects, error behavior, or permissions needed for the write operation.

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?

The description is extremely concise at two sentences. Every sentence provides essential information without redundancy, making it easy to parse quickly.

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?

Given the lack of annotations and output schema, the description is adequate but not comprehensive. It explains the basic function and key prerequisite, but lacks details on parameter encoding, success/error responses, and how to specify a descriptor (only handle is mentioned).

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 high (75%), so the baseline is 3. The description does not add meaningful value beyond the schema; it simply restates the handle concept. It does not clarify the relationship between value_b64 and value_hex or provide usage examples.

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?

The description clearly states the action ('Write') and the resource ('GATT descriptor by handle'). It distinguishes from sibling tools by noting it's rarely needed directly since bleak handles CCCD automatically, which differentiates it from ble_subscribe and other notification-related tools.

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 description provides a prerequisite (BLE_MCP_ALLOW_WRITES=true) and a clear indication of when not to use it (for notify/indicate setup). It does not explicitly list alternative tools but the context is strong enough to guide an agent.

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