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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds valuable behavioral context by specifying the return type ('Returns a list') and advising cursor-based pagination. It does not contradict annotations and goes beyond them to clarify operational behavior.

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 two sentences with zero fluff. The first sentence front-loads the purpose and the critical exclusion, and the second supplies the return/pagination hint. Every clause earns its place, and the structure is ideal for quick agent parsing.

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?

Given the tool has 10 parameters with comprehensive schema descriptions, the description does not need to repeat them. It covers the essential overview, the key distinction from hashtag search, and pagination guidance. The absence of an output schema is acceptable for a list-returning tool. Slight gap is that it doesn't mention other potential alternatives (e.g., profile-specific searches), but that's not required given the rich schema.

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 description coverage is 100%, meaning every parameter has a description. The tool description does not add any parameter-specific semantics beyond what the schema already provides; it only reiterates cursor usage, which is already documented. Thus it sits at the baseline 3, as the schema carries the full burden.

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 states the tool searches X posts by free-text keyword, with a specific verb and resource. It distinguishes itself from hashtag searches by explicitly naming the alternative (twitter.hashtag.list), and the sibling list confirms the presence of such a tool. This leaves no ambiguity about the tool's core function.

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 explicitly instructs when not to use this tool ('not hashtag') and directs to a specific alternative (twitter.hashtag.list). It also implies when to use it (free-text keyword search) and provides pagination guidance ('use cursor when paginated'). This fully meets the criterion of explicit when/when-not and alternatives.

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