tail

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

With no annotations provided, the description carries the full burden, and it discloses the most important behavioral trait: it peeks without consuming the read buffer. It does not mention prerequisites like requiring an open port, but the non-destructive, read-only nature is clearly conveyed.

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?

Two short sentences with no wasted words. The core behavior is front-loaded, and the second sentence adds a practical use case that earns its place.

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 tool is simple, has a complete input schema, and an output schema exists, so return details are covered elsewhere. The only meaningful gap is not explicitly stating that the port must already be open, but the read-buffer terminology and sibling tools make this reasonably inferable.

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 schema already fully documents both parameters. The description adds no parameter-level detail beyond the schema; the word 'lines' aligns with the 'lines' parameter but adds no new 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?

The description uses a specific verb ('Peek') and resource ('last lines received on a port'), and immediately clarifies a distinguishing behavior: it does NOT consume the read buffer. This clearly separates it from read/read_until/query without needing to open the 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?

The second sentence gives a clear context for when to use it: checking what a device has been printing while doing other things. It does not explicitly name alternatives or state when not to use it, but the intended use case is unmistakable.

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