ASTRA

fcs_compare

Read-onlyIdempotent

Compare two species-function pairs in ASTRA to see if they are ordered or incomparable, and explain why the partial order yields that result.

Instructions

Compare two species–function pairs and say why they are ordered — or, just as informatively, why they are incomparable. Incomparability is a result of the partial order, not a gap in it.

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": {
      "a": "<a>",
      "b": "<b>"
    },
    "name": "fcs_compare"
  }
}

Input Schema

Name	Required	Description	Default
`a`	Yes	First pair id, e.g. "1".
`b`	Yes	Second pair id, e.g. "2a".

Schema Changelog

Changes observed during successful MCP inspections.

First observedv3.1.0Sep 23, 2026

TDQS

A3.6/5.0

Behavior4/5

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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, non-destructive, closed-world), so the bar is lower. The description adds genuinely useful behavioral context: the operation returns a rationale for the ordering and explicitly treats incomparability as a legitimate outcome rather than an error, which is valuable for a tool with no output schema.

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?

Two sentences, front-loaded with the verb and the primary object, and the second sentence earns its place by pre-empting a misinterpretation of the result. No filler or restated title.

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?

For a two-parameter, read-only comparison tool with no output schema, the description covers the key things an agent needs: what is compared and the two possible result shapes (ordered with a reason, or incomparable). Only minor gaps remain, such as what happens with invalid or unmatched pair ids.

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%, so both parameters ('a' and 'b' as pair ids) are already documented by the schema. The description adds only the notion that the two arguments are 'species–function pairs' subject to a partial order, which is marginal additional meaning; baseline 3 applies.

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?

States a specific verb and resource ('Compare two species–function pairs') and even describes the nature of the output (a justification for ordering). However, it does not distinguish itself from the many other fcs_* siblings (fcs_report, fcs_taxonomy, fcs_stratify, fcs_levels), so an agent must infer the boundary from the name alone.

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 conveys how to interpret the result ('incomparability is a result of the partial order, not a gap in it') but never says when to call this tool versus its siblings, nor any prerequisites such as needing valid pair ids from fcs_taxonomy or fcs_stratify. No alternatives or exclusions are named.

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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