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

Beyond the annotations it discloses genuinely useful behavior: that redirects are returned but not followed, that outputs preserve HTTP status/headers and JSON/text/base64 bodies, and that the call consumes the same permissions, credits and storage as the underlying API. That credit-consumption note is important given destructiveHint=true and non-idempotent annotations. It does not state rate limits or what happens when expansion fails, leaving some residual gap.

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?

The core capability and the redirect/response behavior are front-loaded in a dense, waste-free block. There is a missing sentence break ("...malicious links Uses the OneSimpleAPI API") and the trailing API-docs sentence is somewhat boilerplate, but nothing is padded.

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 6-parameter tool with nested body/query/files/headers objects and no output schema, the description covers the return shape (status, headers, body encodings), redirect handling, and transport conventions. The main omission is failure behavior and what the `output` formats actually yield, but the essentials for calling it correctly are present.

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 83%, so the schema already documents url, output, content_type and the file structure. The description's "supply parameters in query or body" largely restates what the schema's query/body descriptions already say, adding little new meaning at the parameter level. Baseline 3 applies.

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?

"Expand shortened URLs to reveal the final destination and detect malicious links" gives a specific verb (expand) plus the outcome, which clearly separates it from siblings like api_post_shortener_new (create) and api_get_shortener (list/retrieve). It stops short of naming those siblings explicitly, so it is clear but not fully differentiated.

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?

It gives invocation-level guidance ("Supply API parameters in query or body", "This tool always uses POST; do not supply method") and notes the API key/credit context. It never says when to choose this over api_post_shortener_new or the api_get_shortener reads, so the alternative-selection guidance is only implied by the purpose statement.

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