tail_file

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

Annotations already declare read-only, idempotent, and non-destructive. The description adds useful constraints (file size cap, line limit) and a permission requirement, going beyond annotation details.

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?

Three concise sentences with no filler. The core function is front-loaded, and each sentence adds essential information (operation, limits, permission).

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 description covers operation, constraints, and requirements sufficiently for a simple tail tool. No output schema is present, but the return behavior is obvious; minor gaps like error handling are not critical.

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?

The schema covers path and filter_str, but 'lines' lacks a description. The description clarifies 'last N lines' and 'filtered by substring', adding meaning to lines and filter_str beyond the 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?

The description clearly states the tool tails the last N lines of any text file with optional substring filtering. The verb 'tail' and resource 'text file' distinguish it from siblings like read_file or tail_system_logs.

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 practical context: caps at 50 MB, up to 5000 lines, and requires a specific permission. This helps the agent decide when to use it, although it does not explicitly exclude alternatives like read_file for small files.

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