read_char

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

With no annotations, the description carries the full burden: it does disclose that this is a single non-streaming read and that the value comes back hex-encoded, which is genuine behavioral context. It says nothing about connection prerequisites, error modes (characteristic not found, permission denied, timeout), or whether reads can fail silently.

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 clause pair with zero filler, front-loading the action and then the result. Nothing is wasted and nothing is buried.

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?

The output schema covers the return value, but for a hardware tool with no annotations and 0% parameter documentation the description omits critical call context: prior connection requirement and failure behavior. An agent knows what it does but not the conditions under which it will succeed.

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%, so both 'address' and 'char_uuid' are undocumented, and the description does not compensate at all. Only the word 'characteristic' loosely hints that char_uuid is a characteristic UUID; nothing explains the address format (MAC vs handle) or which device it identifies.

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 (read a characteristic) plus a scope qualifier (once) and the return encoding (hex), which implicitly distinguishes it from the streaming sibling subscribe and from write_char. It does not name any sibling explicitly, so differentiation is inferred rather than stated.

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?

There is no explicit when-to-use guidance, no mention that the device must already be connected (connect/load_device are siblings), and no named alternative. The word 'once' hints at the contrast with subscribe, but the agent must infer prerequisites on its own.

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