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

No annotations are provided, so the description carries the full burden. It discloses that the tool 'ONLY returns the text snippet' and requires manual integration afterward, which is useful behavioral context. However, it doesn't mention potential limitations like rate limits, authentication needs, error handling, or what format the snippet returns (e.g., React code, plain text). For a tool with no annotations, this leaves gaps in understanding its full 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 appropriately sized and front-loaded: it starts with when to use the tool, states its core function, and ends with post-call instructions. Every sentence earns its place—no wasted words. The structure is logical and efficient for an AI agent to parse quickly.

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 no annotations, no output schema, and 5 parameters (though well-documented in schema), the description is moderately complete. It covers the tool's purpose, usage triggers, and post-call actions, but lacks details on output format, error cases, or integration specifics. For a tool that returns UI snippets, more context on what the snippet contains (e.g., React code, dependencies) would be helpful, but it's adequate as a minimum viable description.

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%, so the schema already documents all 5 parameters thoroughly. The description doesn't add any parameter-specific information beyond what's in the schema (e.g., it doesn't explain how 'context' or 'searchQuery' relate to generating the UI snippet). With high schema coverage, the baseline is 3, and the description doesn't compensate with additional param semantics.

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's purpose: 'returns the text snippet for that UI component' when users request new UI components. It provides specific examples of triggers (mentions of /ui, /21, /21st, or component names like button, input, etc.). However, it doesn't explicitly differentiate from sibling tools like '21st_magic_component_refiner' or '21st_magic_component_inspiration' beyond stating this tool 'ONLY returns the text snippet.'

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 provides explicit usage guidelines: 'Use this tool when the user requests a new UI component' with trigger examples, and states 'This tool ONLY returns the text snippet for that UI component.' It also specifies what to do after calling: 'you must edit or add files to integrate the snippet into the codebase.' This gives clear when-to-use instructions and post-call actions, though it doesn't explicitly mention when NOT to use it or name alternatives.

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

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

With no annotations, the description carries the behavioral disclosure burden. It states that no code is generated, that only the text snippet is returned, and that the agent must edit or add files afterward. It does not cover authentication, limits, or exact return shape, but the key behavioral constraints are disclosed.

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 and front-loaded with the trigger conditions. There is some redundancy between 'returns the JSON data' and 'ONLY returns the text snippet', but the overall structure is efficient and the post-call instruction earns its place.

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 two-parameter fetch-like tool with a rich schema and no output schema, this description provides sufficient context: when to use it, what it returns, what it does not do, and what the agent must do afterward. It could be slightly richer on output formatting, but it is largely complete.

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 input schema already documents both required parameters with 100% coverage, so the description adds limited semantic value beyond the schema. The description clarifies that searchQuery is for finding a matching UI component, but this is also reflected in the schema's parameter description.

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 the action as fetching component data and previews from 21st.dev, and it contrasts itself with code generation by stating it does not generate new code. It does not explicitly distinguish itself from the refiner sibling, so it stops short of full differentiation.

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 opens with explicit trigger conditions: 'when the user wants to see component, get inspiration, or /21st'. It does not provide when-not guidance or name alternative tools, but the usage context is clear enough for an agent to select this tool appropriately.

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

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

With no annotations, the description carries the full disclosure burden. It does state the core outcome—'returns redesigned version of the component and instructions on how to implement it'—which implies a read/return behavior rather than a direct write. However, it never says whether the file at absolutePathToRefiningFile is modified, what happens on failure, or any prerequisites, leaving the side-effect profile unclear for a mutating-looking tool.

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?

Two compact sentences with the trigger condition front-loaded in the opening clause ('Use this tool when...'). There is minor redundancy—'improves UI' appears in both sentences—but no filler or irrelevant content.

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?

The definition covers what the tool does, when to use it, and the outcome, and the schema fully documents parameters. But with no output schema and no annotations, the concrete return format of the 'redesigned version and instructions' is unspecified, and side effects on the target file are unstated, leaving the full invocation contract incomplete.

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%, and the schema already documents all three parameters in detail—'context' even includes extraction rules and the 'return an empty string' fallback. The description text adds no parameter-level meaning beyond the schema, so the 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?

The description states specific verbs ('re-design/refine/improve') and a clear resource ('current UI component', 'React component or molecule'), and scopes the tool by excluding big pages. The outcome is also specified: it 'returns redesigned version of the component and instructions on how to implement it.' It does not explicitly distinguish itself from sibling tools (inspiration, builder), so differentiation is inferable rather than stated.

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?

Explicit trigger conditions are given ('when the user requests to re-design/refine/improve current UI component with /ui or /21 commands, or when context is about improving, or refining UI for a React component or molecule') plus a clear exclusion ('NOT for big pages'). It stops short of naming alternatives—an agent is not told to use builder for new components or inspiration for ideas—so the when-not guidance is partial.

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

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

With no annotations to lean on, the description carries the behavioral burden and does well by detailing supported formats, theme variations ('if available'), and the exact structure of results (component name, code, import instructions). It does not cover failure modes or no-result behavior, but the disclosed behavior is sufficient for the agent to anticipate what will happen.

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 well-organized with clear sections for purpose, usage, examples, formats, and output structure. It is slightly longer than strictly necessary because example queries partially repeat the usage triggers, but each section earns its place and the key info is front-loaded in the first sentence.

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 there is no output schema and no annotations, the description does a good job of explaining what the tool returns, including output format options and result fields. However, it mentions 'category filtering' even though the input schema has no category parameter, and it does not explain what happens when a logo is not found, leaving minor but real gaps.

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 schema already describes both parameters (format and queries), so the baseline is 3; the description adds significant value by defining what each format returns (TSX/JSX/SVG), providing concrete example query arrays, and showing how command-style inputs map to the queries parameter. This goes beyond the schema's minimal descriptions.

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 opens with a precise verb and resource: 'Search and return logos in specified format (JSX, TSX, SVG).' It clearly distinguishes itself from sibling tools (which concern component inspiration, refining, and building) by focusing on logo lookup and output formats. The example queries and command styles reinforce exactly what the tool does.

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 'When to use this tool' section explicitly lists two concrete trigger conditions: user types '/logo' command or asks to add a company logo not in the local project. The phrase 'that's not in the local project' provides a clear when-not-to-use condition, effectively excluding cases where the logo is already available locally.

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