mcp

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe, repeatable read operation. The description adds minimal behavioral context beyond this—it mentions the tool provides 'detailed metadata and usage guidance,' which hints at the response format, but doesn't elaborate on rate limits, authentication needs, or error conditions. With annotations covering the core safety profile, the description adds some value but not rich behavioral disclosure.

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 a single, efficient sentence that front-loads the core purpose. It avoids redundancy and wastes no words, though it could be slightly more structured (e.g., by separating metadata from usage guidance). Every part of the sentence contributes to understanding the tool's function, making it appropriately concise for its purpose.

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's low complexity (2 required parameters), rich annotations (read-only, idempotent, non-destructive), and the presence of an output schema (which means return values are documented elsewhere), the description is reasonably complete. It covers what the tool does and the type of information returned. However, it lacks usage guidelines and deeper behavioral context, which prevents a perfect score despite the supportive structured data.

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%, with both parameters ('fontFamily' and 'platform') fully documented in the schema. The description doesn't add any parameter-specific information beyond what's already in the schema—it doesn't explain why both parameters are required or provide additional context about their interaction. Given the high schema coverage, the baseline score of 3 is appropriate, as the description doesn't compensate but also doesn't need to.

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: 'Describes a font family in detail, including its look and feel, supported styles, weights and how to use it.' This specifies the verb ('describes'), resource ('font family'), and scope of information provided. It distinguishes from siblings like 'search_fonts' by focusing on detailed metadata rather than search functionality. However, it doesn't explicitly contrast with other siblings beyond this implicit 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 provides no guidance on when to use this tool versus alternatives. It doesn't mention when to choose 'describe_font' over 'search_fonts' (which likely returns multiple fonts with basic info), nor does it specify prerequisites or contextual constraints. The description simply states what the tool does without addressing usage scenarios or exclusions.

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?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering safety aspects. The description adds that the tool derives colors from key colors and produces a map, which is useful behavioral context beyond annotations. It does not contradict annotations.

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 concise (3 sentences), front-loaded with purpose, and every sentence adds value. It avoids redundancy with the schema and annotations.

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 rich input schema (100% coverage, enums) and the existence of an output schema, the description is complete enough. It covers the core purpose, input format, and output structure, which is sufficient for correct 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 schema already documents all parameters well. The description adds minimal semantic value beyond stating 'one or more key colors' in hex format. It does not explain the role of each parameter or the behavior of optional ones, so a baseline score of 3 is appropriate.

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 it generates a Material Design color scheme from key colors, specifying the input format (hex or named colors) and output structure (map of role names to hex colors). It is specific about the resource (color scheme) and action (generates), and the sibling tools are unrelated, so differentiation is not needed.

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 says 'Always use this when you need to create a color scheme', which is a strong and clear usage directive. No alternative tools exist for color scheme generation among siblings, so it fully guides the agent.

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?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description adds limited behavioral context beyond stating it provides instructions. It does not describe output format or additional constraints.

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 a single concise sentence that front-loads the purpose. No unnecessary words, and it efficiently conveys the tool's function.

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 no parameters and annotations are comprehensive, the description adequately indicates the tool's purpose. However, it could be more specific about the nature of the instructions (e.g., code snippets, best practices), so slightly lacking in completeness.

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?

No parameters exist, and schema coverage is 100% by default. Baseline for zero parameters is 4; the description does not need to add parameter info.

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 provides instructions on using Material Icons and Material Symbols on the web. It specifies the verb 'provides instructions' and the resource, distinguishing it from sibling tools like search_icons and describe_font.

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 implies the tool is for obtaining usage instructions but does not explicitly state when to use it versus alternatives like search_icons or typeset. No 'when-not-to-use' or alternative guidance is provided.

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?

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description doesn't need to reiterate safety. It adds no extra behavioral context (e.g., pagination, result limits), but is consistent and non-contradictory.

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?

Single, front-loaded sentence with no wasted words. Every part is necessary and efficient.

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 rich schema (100% coverage, enums, output schema) and annotations, the description covers the core purpose. It could mention result formatting or pagination, but not essential for a search tool with output 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?

The input schema has 100% coverage with detailed descriptions and enum values. The description adds no new parameter meaning beyond 'matching categories and/or languages', which is already in the schema.

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 it finds fonts matching categories and/or languages, with a specific verb and resource. It distinguishes from siblings like describe_font (describes a specific font) and search_icons (searches icons).

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?

No explicit guidance on when to use this tool versus alternatives, such as when not to use it or preferred contexts. The description only implies usage for font discovery by categories/languages.

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?

Annotations indicate readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering safety and idempotency. The description adds minimal behavioral context by specifying the search is based on 'keywords that describe their usage, style, or shape,' but doesn't elaborate on aspects like rate limits, authentication needs, or result ordering. It doesn't contradict annotations, so it earns a baseline score for adding some value beyond the structured data.

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 a single, efficient sentence that directly states the tool's purpose without unnecessary words. It's front-loaded with the core action and resource, and every part of the sentence contributes meaningfully. There's no redundancy or wasted space, making it highly concise and well-structured.

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's complexity (a search function with 2 parameters), rich annotations (covering read-only, idempotent, and non-destructive traits), and the presence of an output schema (which handles return values), the description is reasonably complete. It specifies the resource type and matching criteria, but lacks usage guidelines and deeper behavioral context, which slightly reduces completeness. However, it's adequate for a tool with good structured support.

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 the input schema fully documents both parameters ('tags' and 'iconSet') with detailed descriptions. The description doesn't add any parameter-specific information beyond what's in the schema, such as syntax or format details. According to the rules, with high schema coverage, the baseline score is 3, as the schema handles the heavy lifting.

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: 'Finds appropriate Material Design icons matching keywords that describe their usage, style, or shape.' It specifies the verb ('Finds'), resource ('Material Design icons'), and matching criteria ('keywords that describe their usage, style, or shape'). However, it doesn't explicitly differentiate from sibling tools like 'search_fonts' beyond the resource type, which is why it doesn't reach a score of 5.

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 no guidance on when to use this tool versus alternatives. It doesn't mention sibling tools like 'search_fonts' or 'icons_instructions', nor does it specify any prerequisites, exclusions, or contextual triggers for usage. The only implied usage is based on the purpose statement, which is insufficient for clear decision-making.

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?

Annotations already declare readOnlyHint=true and idempotentHint=true, so the tool is safe to call. The description adds that it is 'CRITICAL' and 'mandatory,' which is usage context rather than behavioral disclosure. It doesn't describe potential side effects or further behavioral traits beyond the annotations.

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 a single sentence that is front-loaded with a directive ('CRITICAL: You MUST...'). It is fairly concise but could be shortened by removing redundant emphasis on 'mandatory.' Still, it communicates purpose effectively.

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 one parameter, good annotations, and an output schema, the description covers the essential context: what it provides and when to use it. It lacks details on the exact output format, but the output schema presumably handles that, so completeness is adequate.

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%: the platform parameter is described in the schema with enum options. The tool description does not add any additional meaning or constraints beyond what the schema already provides, so baseline 3 is appropriate.

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 that the tool provides 'mandatory layout, modular scale, multi-vibe font selection, and proximity grouping blueprints' for UI design tasks. It distinguishes from sibling tools like search_fonts and describe_font by specifying a unique output (design system blueprints).

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 says to call the tool 'on every UI design or HTML/CSS code generation task,' giving clear when-to-use guidance. However, it does not mention when not to use or provide comparisons to alternatives, so score 4.

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