Introduce Elicitation capability #520
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@ihrpr fyi rebased and fixed up the FYI in addition to the stale resumption token issue (#530), I think there may be an issue when a request times out mid-elicitation. This was hard to repro and I'm not sure if it's due to the example code or deeper in the server logic. |
We can set timeouts for requests and cover with tests |
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I've implemented this feature in a demo https://github.com/gzuuus/elicitation-demo-mcp |
dsp-ant
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Jun 16, 2025
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| } else { | ||
| // Parse the value based on type | ||
| let parsedValue: unknown; | ||
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| if (field.type === 'boolean') { | ||
| parsedValue = answer.toLowerCase() === 'true' || answer.toLowerCase() === 'yes' || answer === '1'; | ||
| } else if (field.type === 'number') { | ||
| parsedValue = parseFloat(answer); | ||
| if (isNaN(parsedValue as number)) { | ||
| throw new Error(`${fieldName} must be a valid number`); | ||
| } | ||
| } else if (field.type === 'integer') { | ||
| parsedValue = parseInt(answer, 10); | ||
| if (isNaN(parsedValue as number)) { | ||
| throw new Error(`${fieldName} must be a valid integer`); | ||
| } | ||
| } else if (field.enum) { | ||
| if (!field.enum.includes(answer)) { | ||
| throw new Error(`${fieldName} must be one of: ${field.enum.join(', ')}`); | ||
| } | ||
| parsedValue = answer; | ||
| } else { | ||
| parsedValue = answer; | ||
| } | ||
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| content[fieldName] = parsedValue; | ||
| } | ||
| } catch (error) { | ||
| console.log(`❌ Error: ${error}`); | ||
| // Continue to next attempt | ||
| break; | ||
| } | ||
| } | ||
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| if (inputCancelled) { | ||
| return { action: 'cancel' }; | ||
| } | ||
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| // If we didn't complete all fields due to an error, try again | ||
| if (Object.keys(content).length !== Object.keys(properties).filter(name => | ||
| required.includes(name) || content[name] !== undefined | ||
| ).length) { | ||
| if (attempts < maxAttempts) { | ||
| console.log('Please try again...'); | ||
| continue; | ||
| } else { | ||
| console.log('Maximum attempts reached. Declining request.'); | ||
| return { action: 'decline' }; | ||
| } | ||
| } | ||
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| // Validate the complete object against the schema | ||
| const isValid = validate(content); | ||
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| if (!isValid) { | ||
| console.log('❌ Validation errors:'); | ||
| validate.errors?.forEach(error => { | ||
| console.log(` - ${error.dataPath || 'root'}: ${error.message}`); | ||
| }); | ||
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| if (attempts < maxAttempts) { | ||
| console.log('Please correct the errors and try again...'); | ||
| continue; | ||
| } else { | ||
| console.log('Maximum attempts reached. Declining request.'); | ||
| return { action: 'decline' }; | ||
| } | ||
| } | ||
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| // Show the collected data and ask for confirmation | ||
| console.log('\n✅ Collected data:'); | ||
| console.log(JSON.stringify(content, null, 2)); | ||
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| const confirmAnswer = await new Promise<string>((resolve) => { | ||
| readline.question('\nSubmit this information? (yes/no/cancel): ', (input) => { | ||
| resolve(input.trim().toLowerCase()); | ||
| }); | ||
| }); | ||
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| if (confirmAnswer === 'yes' || confirmAnswer === 'y') { | ||
| return { | ||
| action: 'accept', | ||
| content, | ||
| }; | ||
| } else if (confirmAnswer === 'cancel' || confirmAnswer === 'c') { | ||
| return { action: 'cancel' }; | ||
| } else if (confirmAnswer === 'no' || confirmAnswer === 'n') { | ||
| if (attempts < maxAttempts) { | ||
| console.log('Please re-enter the information...'); | ||
| continue; | ||
| } else { | ||
| return { action: 'decline' }; | ||
| } | ||
| } | ||
| } | ||
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| console.log('Maximum attempts reached. Declining request.'); | ||
| return { action: 'decline' }; | ||
| }); |
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This seems very complex. Should we use something like https://www.npmjs.com/package/@inquirer/prompts in order to make it easier?
There was a problem hiding this comment.
Took a quick stab at this #637 but I don't think it's a good change - it's not significantly simpler, and too opinionated w.r.t. what clients should be doing IMO. As a super simple demo of the flow through the protocol I think this is fine
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Implementing spec:
modelcontextprotocol/modelcontextprotocol#382