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

Annotations already declare readOnlyHint, openWorldHint=false, and idempotentHint, and the description reinforces this with 'Nothing is fetched or resolved', which is meaningful confirmation that no network egress occurs. It also discloses the hard cap of 8 links processed, a behavioral limit not present in any structured field. It stops short of describing how many inputs it can process per call or how truncated text is handled.

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?

Front-loaded with the action and scope, followed by a compact enumeration of heuristics and a one-clause safety assertion. The signal list is dense but each item is a distinct, useful discriminator; no redundant restatement of the name or title.

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 one-parameter, annotation-covered, no-network tool this covers what the agent needs: what is extracted, what is examined, what is explicitly not done. With no output schema, it would help to hint at the result shape (per-link verdict versus plain list), which is the only notable omission.

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 single 'text' parameter is fully described in the schema (100% coverage), including a 12000-character maxLength and the requirement of at least one link. The description's 'up to 8 links' relates to output volume rather than parameter meaning, so it adds little beyond the schema; baseline 3 applies when schema 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?

States a specific verb and resource ('Extract up to 8 links from a text') and enumerates the exact signals judged (brand lookalikes, raw IP hosts, shorteners, encoded IDNs, risky suffixes, subdomain/hyphen counts, credential-style paths). The purpose is unmistakable, but it never mentions the sibling scam_check, so the agent must infer the boundary between link-level and scam-level checking.

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 is implied by the 'judge by shape alone' framing and the 'Nothing is fetched or resolved' constraint, which tells the agent this is safe for untrusted text. However, there is no explicit when-to-use/when-not statement and no routing to the alternative scam_check tool, leaving selection between the two siblings to inference.

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