Supernova Cosmology MCP Server

plot_sn_lightcurve

Plots a Type Ia supernova multi-band light curve by downloading per-SN photometry on demand and generating a publication-style chart with one color per band in flux or magnitude space.

Instructions

Plot a SN Ia multi-band light curve (per-SN photometry).

Downloads the light curve on demand (same as fetch_sn_lightcurve) and makes a publication-style
plot with one colour per band. Flux space (default) shows the SALT2 flux calibration; magnitude
space inverts the y-axis and uses mag where available.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "output_dir": "<output_dir>",
      "cid": "<cid>"
    },
    "name": "plot_sn_lightcurve"
  }
}

Input Schema

Name	Required	Description	Default
`cid`	Yes	SN candidate ID.
`dataset`	No	pantheonplus or des5yr.	pantheonplus
`flux_space`	No	Plot in flux (True) or magnitude (False, inverted axis).
`output_dir`	Yes	Directory for the PNG.

Output Schema

Name	Required	Description	Default
`files`	Yes
`status`	Yes
`message`	Yes
`metadata`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 6, 2026

TDQS

A3.9/5.0

Behavior3/5

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

No annotations are supplied, so the description carries the full burden. It does disclose a real side effect (the light curve is downloaded on demand, i.e. network/IO cost) and explains plot semantics per space, but says nothing about where the PNG lands relative to output_dir, whether an existing file is overwritten, failure behavior for an unknown cid, or runtime.

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

Conciseness4/5

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

Three short sentences, front-loaded with purpose and then the download behavior, with zero filler. The second half of the last sentence partially restates the flux_space schema description (inverted y-axis), which is the only redundancy.

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

Completeness4/5

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

With an output schema present, return values need no explanation, and the description covers the download-plus-render pipeline and axis semantics adequately for a 4-parameter tool. Minor gaps remain around output file naming and error conditions for an invalid cid.

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

Parameters4/5

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

Schema coverage is 100%, so baseline is 3, but the description goes slightly beyond the schema by stating that flux space uses the SALT2 flux calibration and that magnitudes are used 'where available' — information not present in the parameter descriptions. dataset and output_dir are left entirely to the schema.

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

Purpose5/5

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

"Plot a SN Ia multi-band light curve (per-SN photometry)" gives a concrete verb plus resource, and the body explicitly ties it to the sibling fetch_sn_lightcurve by noting it downloads the same data on demand. An agent can distinguish 'I want the plotted figure' from 'I want the raw photometry' without opening either schema.

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

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied: reach for this when a publication-style per-SN figure is needed, and the mention of fetch_sn_lightcurve hints at the data-only alternative. However, there is no explicit when-to-use/when-not statement, no note on which dataset to prefer, and no prerequisite such as a prior fetch or auth.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.