fetch_url

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

With no annotations, description fully discloses behaviors: GitHub API vs. fetch cascade, markdown output, 8000-char truncation, 24-hour caching, and blocked domain refusal. This is comprehensive for a fetch tool.

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, front-loaded with main action. Each sentence adds distinct, valuable information. No wasted words.

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?

Description covers input (via schema), behavior, and output format (markdown). Without output schema, it could elaborate on error handling or response structure, but current coverage is strong for a fetch tool.

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% (both parameters described in schema). Description adds context about URL handling (e.g., cascade) but does not significantly enhance parameter meaning 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?

Description clearly states 'Fetch and extract readable content from any URL.' It specifies the verb (fetch, extract) and resource (URL content), and distinguishes from siblings by detailing GitHub API handling and fetch cascade.

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?

Description implies usage for fetching content from URLs but does not explicitly state when not to use or suggest alternatives. Sibling tool names are listed but not referenced in the description.

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