tail

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

Adds read-only guarantee ('Read-only, no side effects') which complements annotations, explains output format options (JSON vs raw via --raw), and mentions negative-N behavior.

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?

Four sentences, front-loaded with core function, no redundant lines; every sentence adds distinct value.

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?

Describes return format (JSON line array or raw), usage context, and mentions related tools; no output schema but description compensates fully.

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 coverage is 100%, but description adds semantic context: default 10 lines, raw flag effect, and negative-N skipping, enhancing parameter understanding beyond schema.

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?

Clearly states it returns last N lines of files or stdin as JSON, and explicitly distinguishes from sibling tools like 'head' ('Not for viewing file beginnings — use 'head'.') and references 'cat'.

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?

Provides explicit use case ('view recent file additions or check log tails') and when not to use ('Not for viewing file beginnings'), with clear alternatives listed.

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