emoji_lookupLook up an emoji by :shortcode: (e.g. ":fire:" or "fire") to get the character + keywords, OR pass an emoji character to get its shortcode/name. Keyless, offline.
| Name | Required | Description | Default |
|---|---|---|---|
| input | Yes | A :shortcode:, a bare shortcode, or an emoji character. |
Changes observed during successful MCP inspections.
Input schema / examplesAdded value: +[
+ {
+ "input": ":fire:"
+ },
+ {
+ "input": "π"
+ }
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate readOnly, idempotent, openWorld, and non-destructive behavior. The description adds valuable context: 'Keyless, offline,' and specifies the return format (character + keywords or shortcode/name). This goes beyond the annotations and fully discloses the tool's behavior in a transparent manner.
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 extremely concise: two short sentences that front-load the key information. Every word serves a purpose, with no filler or redundancy.
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 simplicity (one parameter, no output schema, annotations covering safety), the description covers all necessary information: input formats, return types, keyless and offline nature. No gaps 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?
The input schema has 100% coverage for the single parameter 'input', with a description that matches the tool's text. The description adds examples but does not provide significant new meaning beyond the schema. Baseline 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 the tool's purpose: 'Look up an emoji by :shortcode:' or by passing an emoji character to get its name. It specifies two distinct modes of operation, making it easy to understand what the tool does. The sibling list includes 'search_emoji', which suggests a different functionality (search vs. exact lookup), providing implicit distinction.
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 clear context on when to use the tool: for shortcode-to-emoji or emoji-to-shortcode lookups. However, it does not explicitly state when not to use it or mention alternatives like 'search_emoji'. The guidance is implied but not exhaustive.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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