# AI Persona using Categories tool- "An empty string is not a valid JSON string"

**URL:** <https://meta.discourse.org/t/ai-persona-using-categories-tool-an-empty-string-is-not-a-valid-json-string/352565>\
**Category:** Bug\
**Tags:** ai, ai-bot\
**Created:** [February 16, 2025, 3:58pm UTC](https://meta.discourse.org/t/ai-persona-using-categories-tool-an-empty-string-is-not-a-valid-json-string/352565 "2025-02-16T15:58:24Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![markschmucker](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/markschmucker/32/141599_2.png) [@markschmucker](https://meta.discourse.org/u/markschmucker)\
**Post date:** [February 16, 2025, 3:58pm UTC](https://meta.discourse.org/t/ai-persona-using-categories-tool-an-empty-string-is-not-a-valid-json-string/352565/1 "2025-02-16T15:58:24Z")

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I consistently get an error for any Persona trying to use the Categories tool. This includes the built-in Forum Helper. Up to date with 3.5.0.beta1-dev.

 ![image](https://global.discourse-cdn.com/meta/original/4X/6/9/5/695068a9e9aea48dbeda14c526502d0a04511dff.png)

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**Author:** ![sam](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/sam/32/102149_2.png) [@sam](https://meta.discourse.org/u/sam)\
**Post date:** [February 16, 2025, 10:38pm UTC](https://meta.discourse.org/t/ai-persona-using-categories-tool-an-empty-string-is-not-a-valid-json-string/352565/2 "2025-02-16T22:38:09Z")

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Confirmed, this is a bug in native tools for sonnet/haiku. will have a look.

Work around is to use XML tools.

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<div class="post-metadata">

**Author:** ![sam](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/sam/32/102149_2.png) [@sam](https://meta.discourse.org/u/sam)\
**Post date:** [February 17, 2025, 1:09am UTC](https://meta.discourse.org/t/ai-persona-using-categories-tool-an-empty-string-is-not-a-valid-json-string/352565/3 "2025-02-17T01:09:11Z")

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Fix is here:

[https://github.com/discourse/discourse-ai/pull/1128](https://github.com/discourse/discourse-ai/pull/1128)

Eval for no param tools was added here:

[https://github.com/discourse/discourse-ai-evals/pull/2](https://github.com/discourse/discourse-ai-evals/pull/2)

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**Author:** ![Falco](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/falco/32/179432_2.png) [@Falco](https://meta.discourse.org/u/Falco)\
**Post date:** [February 22, 2025, 11:00am UTC](https://meta.discourse.org/t/ai-persona-using-categories-tool-an-empty-string-is-not-a-valid-json-string/352565/4 "2025-02-22T11:00:53Z")

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