# `MCP008` List all tags
{bdg-ref-info}`mcp | tools <mcp:tools>`
{bdg-ref-info}`mcp | discovery <mcp:discovery>`
> I would like to discover what tags exist in the specification so I can explore
> requirements by theme. For example, "what tags are used?" helps me understand
> how requirements are organized before I search for specific tags.
> 

The user shall be able to retrieve a list of all tags used in the specification.

The MCP server shall expose a tool named `list_all_tags` that returns
all unique tags used across all requirements.

The response shall be a sorted list of unique tag strings.

Tags with subtags (e.g., "output:pdf") shall be listed as complete tags,
not split into parts.

If no requirements have tags, an empty list shall be returned.


:::{dropdown} Properties
:icon: note
:color: primary

__author__: Claude

__since__: `0.2.0`

:::
:::{dropdown} Tested by
:open: 
:icon: check-circle-fill
:color: success

- [`TMCP024` list_all_tags returns unique tags sorted](/tests/TMCP024)
- [`TMCP025` list_all_tags returns empty list when no tags](/tests/TMCP025)
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:::{dropdown} Source
:icon: file-code
:color: info

__Source file__: [`specs/mcp/discovery.yaml`](https://github.com/agagniere/speky/blob/master/specs/mcp/discovery.yaml)

__Loaded from__: [`speky_mcp`](https://github.com/agagniere/speky/blob/master/specs/mcp/mcp.toml)

__Implemented in:__
{fab}`python` [`handle_list_all_tags`](https://github.com/agagniere/speky/blob/master/python/speky_mcp/tools.py#L204)
:::