read_log

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

With no annotations provided, the description carries the full behavioral burden, and it does well: discloses the efficiency trait ('reads backwards from the end without loading the whole file into memory'), the case-insensitive grep behavior is implied, and it flags the tool as safe ('Safely'). It doesn't disclose much about return format or error behavior, but the described caching/efficiency benefit is genuinely useful behavioral context.

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 sentences, each earning its place: the first states function, the second explains efficiency/behavior, the third gives concrete use guidance. Well front-loaded with the primary purpose in the first clause and no redundant filler.

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?

For a simple 3-param read tool with 100% schema coverage and clear sibling differentiation, the description is complete. It covers purpose, use cases, alternatives, and performance characteristics. No output schema exists, but the tool's return (filtered tail lines) is self-evident from the description.

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% for all 3 parameters (path, lines, grep), so the baseline is 3. The description adds context about the grep being case-insensitive (echoed in schema) and the tail-backwards behavior, but doesn't add substantial new parameter meaning beyond what the schema already documents. No major compensation needed since coverage is complete.

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 does tail+grep on log files, with specific verb ('read the end'), resource ('log file'), and mode ('tail', optionally 'grep'). It also explicitly distinguishes from siblings by naming read_config and explaining when NOT to use it, which differentiates it from alternatives.

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?

Explicitly states when to use ('Use this instead of read_config for files like /var/log/syslog, nginx access logs') and names the alternative tool (read_config), establishing clear boundary conditions. The guidance about 'any file that could be massive' provides practical selection criteria.

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