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pl_dotplot

Visualize gene expression patterns across cell groups using dot plots to compare expression levels and cell fractions in single-cell RNA-seq data analysis.

Instructions

Plot dot plot of expression values per gene for each group.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
figsizeNoFigure size. Format is (width, height).
color_mapNoColor map to use for continuous variables.
paletteNoColors to use for plotting categorical annotation groups.
vmaxNoThe value representing the upper limit of the color scale.
vminNoThe value representing the lower limit of the color scale.
vcenterNoThe value representing the center of the color scale.
legend_fontsizeNoNumeric size in pt or string describing the size.
legend_fontweightNoLegend font weight. A numeric value in range 0-1000 or a string.bold
legend_locNoLocation of legend, either 'on data', 'right margin' or a valid keyword for the loc parameter.right margin
legend_fontoutlineNoLine width of the legend font outline in pt.
var_namesNovar_names should be a valid subset of adata.var_names or a mapping where the key is used as label to group the values.
groupbyYesThe key of the observation grouping to consider.
use_rawNoUse raw attribute of adata if present.
logNoPlot on logarithmic axis.
dendrogramNoIf True or a valid dendrogram key, a dendrogram based on the hierarchical clustering between the groupby categories is added.
gene_symbolsNoColumn name in .var DataFrame that stores gene symbols.
var_group_positionsNoUse this parameter to highlight groups of var_names with brackets or color blocks between the given start and end positions.
var_group_labelsNoLabels for each of the var_group_positions that want to be highlighted.
layerNoName of the AnnData object layer that wants to be plotted.
expression_cutoffNoExpression cutoff that is used for binarizing the gene expression.
mean_only_expressedNoIf True, gene expression is averaged only over the cells expressing the given genes.
standard_scaleNoWhether or not to standardize that dimension between 0 and 1.
swap_axesNoBy default, the x axis contains var_names and the y axis the groupby categories. By setting swap_axes then x are the groupby categories and y the var_names.
dot_maxNoThe maximum size of the dots.
dot_minNoThe minimum size of the dots.
smallest_dotNoThe smallest dot size.
var_group_rotationNoLabel rotation degrees. By default, labels larger than 4 characters are rotated 90 degrees.
colorbar_titleNoTitle for the color bar. New line character (\n) can be used.Mean expression in group
size_titleNoTitle for the size legend. New line character (\n) can be used.Fraction of cells in group (%)

Implementation Reference

  • Generic handler function for all pl_ tools including pl_dotplot. Dispatches to sc.pl.dotplot based on func='pl_dotplot', prepares arguments, executes the plot, saves figure to path, and logs the operation.
    def run_pl_func(ads, func, arguments):
        """
        Execute a Scanpy plotting function with the given arguments.
        
        Parameters
        ----------
        adata : AnnData
            Annotated data matrix.
        func : str
            Name of the plotting function to execute.
        arguments : dict
            Arguments to pass to the plotting function.
            
        Returns
        -------
        The result of the plotting function.
        """
        adata = ads.adata_dic[ads.active]
        if func not in pl_func:
            raise ValueError(f"Unsupported function: {func}")
    
        run_func = pl_func[func]
        parameters = inspect.signature(run_func).parameters
        kwargs = {k: arguments.get(k) for k in parameters if k in arguments}    
    
        if "title" not in parameters:
            kwargs.pop("title", False)    
        kwargs.pop("return_fig", True)
        kwargs["show"] = False
        kwargs["save"] = ".png"
        try:
            fig = run_func(adata, **kwargs)
            fig_path = set_fig_path(func, **kwargs)
            add_op_log(adata, run_func, kwargs)
            return fig_path 
        except Exception as e:
            raise e
        return fig_path
  • Pydantic model defining the input schema and validation for the pl_dotplot tool parameters, extending BaseMatrixModel with dotplot-specific fields like expression_cutoff, dot_max, etc.
    class DotplotModel(BaseMatrixModel):
        """Input schema for the dotplot plotting tool."""
        
        expression_cutoff: float = Field(
            default=0.0,
            description="Expression cutoff that is used for binarizing the gene expression."
        )
        
        mean_only_expressed: bool = Field(
            default=False,
            description="If True, gene expression is averaged only over the cells expressing the given genes."
        )
        
        standard_scale: Optional[Literal['var', 'group']] = Field(
            default=None,
            description="Whether or not to standardize that dimension between 0 and 1."
        )
        
        swap_axes: bool = Field(
            default=False,
            description="By default, the x axis contains var_names and the y axis the groupby categories. By setting swap_axes then x are the groupby categories and y the var_names."
        )
        
        dot_max: Optional[float] = Field(
            default=None,
            description="The maximum size of the dots."
        )
        
        dot_min: Optional[float] = Field(
            default=None,
            description="The minimum size of the dots."
        )
        
        smallest_dot: Optional[float] = Field(
            default=None,
            description="The smallest dot size."
        )
        var_group_rotation: Optional[float] = Field(
            default=None,
            description="Label rotation degrees. By default, labels larger than 4 characters are rotated 90 degrees."
        )
        
        colorbar_title: Optional[str] = Field(
            default='Mean expression\nin group',
            description="Title for the color bar. New line character (\\n) can be used."
        )
        
        size_title: Optional[str] = Field(
            default='Fraction of cells\nin group (%)',
            description="Title for the size legend. New line character (\\n) can be used."
        )
  • Registers the pl_dotplot tool object with MCP types.Tool, specifying name, description, and input schema from DotplotModel.
    pl_dotplot = types.Tool(
        name="pl_dotplot",
        description="Plot dot plot of expression values per gene for each group.",
        inputSchema=DotplotModel.model_json_schema(),
    )
  • Maps tool name 'pl_dotplot' to the underlying Scanpy function sc.pl.dotplot, used by the handler to dispatch execution.
    pl_func = {
        "pl_pca": sc.pl.pca,
        "pl_embedding": sc.pl.embedding,  # Add the new embedding function
        "diffmap": sc.pl.diffmap,
        "pl_violin": sc.pl.violin,
        "pl_stacked_violin": sc.pl.stacked_violin,
        "pl_heatmap": sc.pl.heatmap,
        "pl_dotplot": sc.pl.dotplot,
        "pl_matrixplot": sc.pl.matrixplot,
        "pl_tracksplot": sc.pl.tracksplot,
        "pl_scatter": sc.pl.scatter,
        "embedding_density": sc.pl.embedding_density,
        "rank_genes_groups": sc.pl.rank_genes_groups,
        "pl_rank_genes_groups_dotplot": sc.pl.rank_genes_groups_dotplot,  # Add function mapping
        "pl_clustermap": sc.pl.clustermap,
        "pl_highly_variable_genes": sc.pl.highly_variable_genes,
        "pl_pca_variance_ratio": sc.pl.pca_variance_ratio,
    }
  • MCP server call_tool handler dispatches 'pl_dotplot' (in pl_tools) to run_pl_func(ads, 'pl_dotplot', arguments), providing the execution entrypoint for the tool.
    async def call_tool(
        name: str, arguments
    ):
        try:
            logger.info(f"Running {name} with {arguments}")
            if name in io_tools.keys():            
                res = run_io_func(ads, name, arguments)
            elif name in pp_tools.keys():
                res = run_pp_func(ads, name, arguments)
            elif name in tl_tools.keys():
                res = run_tl_func(ads, name, arguments) 
            elif name in pl_tools.keys():
                res = run_pl_func(ads, name, arguments)
            elif name in util_tools.keys():            
                res = run_util_func(ads, name, arguments)
            elif name in ccc_tools.keys():            
                res = run_ccc_func(ads.adata_dic[ads.active], name, arguments)
            output = str(res) if res is not None else str(ads.adata_dic[ads.active])
            return [
                types.TextContent(
                    type="text",
                    text=str({"output": output})
                )
            ]
        except Exception as error:
            logger.error(f"{name} with {error}")
            return [
                types.TextContent(
                    type="text",
                    text=str({"Error": error})
                )
            ]
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. The description only states the plotting action without mentioning whether this creates a file, displays a plot, requires specific data structures, has side effects, or what the output format is. For a complex plotting tool with 29 parameters, this lack of behavioral context is a significant gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is extremely concise - a single sentence that directly states the tool's purpose. There's no wasted language or unnecessary elaboration. It's appropriately sized for a plotting tool description and front-loads the essential information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (29 parameters, no annotations, no output schema), the description is inadequate. It doesn't explain what the tool returns (plot object? file path? display?), what data structures it expects, or any prerequisites. For a visualization tool with many configuration options, the description should provide more context about the tool's behavior and output.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, meaning all 29 parameters are documented in the schema itself. The description adds no parameter information beyond what's already in the schema. According to the rules, when schema coverage is high (>80%), the baseline score is 3 even with no parameter information in the description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'Plot dot plot of expression values per gene for each group.' It specifies the verb ('Plot'), resource ('dot plot'), and scope ('expression values per gene for each group'). However, it doesn't differentiate from sibling tools like 'pl_rank_genes_groups_dotplot' or 'ccc_dot_plot', which prevents a perfect score.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

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. With multiple plotting tools in the sibling list (pl_heatmap, pl_matrixplot, pl_rank_genes_groups_dotplot, etc.), there's no indication of when a dot plot is appropriate versus other visualization types. The description only states what the tool does, not when to choose it.

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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