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

Annotations already indicate readOnlyHint and openWorldHint, but the description adds substantial behavioral detail: 365-day exact match, 30-day fallback, archive flagging, hash type auto-detection, case-insensitivity, and a security warning that returned field values are attacker-authored and must be treated as data, not instructions.

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?

Every sentence earns its place: primary purpose is front-loaded, matching behavior is explained precisely, use case is stated, and the security warning is included. No fluff or redundant repetition of schema details.

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 single-parameter read-only check tool with no output schema, the description is nearly complete: it explains matching window, fallback behavior, archive handling, hash validation, and output trust concerns. It stops short of enumerating exact response fields, but an invoking agent has enough to use the tool correctly.

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 already fully documents the hash parameter, including length, case-insensitivity, and invalid input behavior. The description adds extra semantic value by explaining hash type auto-detection from length and exact hex matching, which goes beyond the raw 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 opens with a specific verb and resource: 'Check whether a file hash (MD5 or SHA-256) appears in the TweetFeed corpus.' It clearly distinguishes this from sibling check_ip and check_url tools by targeting file hashes specifically.

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 clear context: 'Useful for confirming if a binary sample has been shared by the public infosec Twitter/X community.' This tells the agent when to use it, though it does not explicitly name alternatives or exclusions.

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