Fetch a BLE characteristic's data, returned as base64, hex, and byte count for inspection or analysis.
Fetch a characteristic's contents; the reply carries them as base64, hex, and a plain byte count.
| Name | Required | Description | Default |
|---|---|---|---|
| char_uuid | Yes | ||
| timeout_s | No | ||
| connection_id | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It discloses the reply encoding, but says nothing about whether the read is blocking, what happens on a disconnected or unauthorised connection, how the timeout_s budget behaves, or what errors surface. For a BLE read this is a meaningful gap.
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 compact sentence with the action front-loaded and no filler. The trailing clause about base64/hex/byte count is largely redundant with the existing output schema, which slightly dilutes it.
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?
An output schema exists, so return values need not be explained, and the tool is a simple read. Still, with no annotations, no parameter documentation, and no connection precondition stated, an agent lacks the context to call it correctly in failure or timeout scenarios.
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 0% across three parameters (connection_id, char_uuid, timeout_s), so the description must compensate and does not: it explains none of them. timeout_s in particular is left entirely ambiguous despite having a default.
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: 'Fetch a characteristic's contents.' The word 'characteristic' naturally distinguishes it from the sibling lw_ble_read_descriptor and from lw_ble_write, but it doesn't explicitly name those siblings or route between them.
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?
No when-to-use guidance, no stated prerequisites (e.g. an active connection from lw_ble_connect), and no mention of when to prefer lw_ble_read_descriptor or lw_ble_poll_notifications instead. The required connection_id hints at a precondition but nothing is explained.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.