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

Annotations establish this is a non-read-only, non-destructive, non-idempotent write; the description adds valuable context beyond them: the paste is unlisted, anyone with the link can read it, and free accounts are restricted to the default 1M expiry. It does not cover failure modes or rate limits, so not a 5.

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 short sentences: what it does and returns, then visibility, then account constraints. Front-loaded and every sentence carries distinct information with no repetition of schema text.

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 5-parameter create tool with no output schema, it covers the return value (shareable link), visibility model, and tier restrictions. Minor gaps remain—no mention of error behavior or password interaction at the behavioral level—but an agent has enough to call it 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?

Schema coverage is 100% so the baseline is 3, but the description adds constraints the schema does not encode: that 1M is the mandatory default on free accounts and other expiries require Pro. That is real semantic value about the expire parameter.

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?

Specific verb and resource ('Create a paste on Pastes.io') plus the outcome ('return its shareable link'). The write verb immediately separates it from get_paste, list_pastes and delete_paste without needing their schemas.

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?

Usage context is clear: it is the creation entry point and the expiry tiers tell the agent when certain options are legal. It stops short of naming alternatives (e.g. use get_paste to read it back), so it is not a full when/when-not statement.

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