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

The annotations already indicate read-only and non-destructive behavior; the description adds useful access and quota context: no API key needed, a session limit of 20 queries, and a mix of price/free messaging. This is valuable beyond the annotations, though the relationship between '0.01 USDC/query' and 'FREE preview' could be clearer.

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 description is short but padded with repetitive, promotional language: 'call this now', 'FREE preview — no key, no payment', and 'Try one of the sample questions now'. It repeats the no-key point and mixes pricing with free messaging, making it less clear and more cluttered than necessary.

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 tool with two optional parameters, no output schema, and read-only annotations, the description gives enough to attempt a call: it says no auth is needed, provides sample questions, and notes a session limit. It does not describe the response shape or clarify how this preview relates to the paid data_session_* tools, which is a meaningful gap for selection and invocation.

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. The description adds concrete example values for the `question` parameter ('What clinical trials were posted today?' and 'Show newly recruiting studies'), which helps an agent phrase valid input. It does not add to `slug`, but the schema already documents its default behavior.

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 clearly identifies a specific listing (trialwatch) and frames the tool as a free preview of that data with sample questions. It lacks a crisp formal statement like 'previews a listing's public metadata', but the intent is understandable and the schema description reinforces it. It does not differentiate itself from sibling session tools.

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?

The description strongly implies when to use it: when you want a free, no-key preview before any paid session. Phrases like 'No API key needed — call this now' and 'FREE preview — no key, no payment' provide clear context. However, it never names alternative tools or says when not to use this tool, so the guidance is implied rather than explicit.

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